A new approach to fabricate copper, indium, gallium diselenide (CIGSe) solar cells on conductive fluorine-doped tin oxide (FTO) reached an efficiency of over 6% for a champion photovoltaic device. Commercial oxide nanoparticles are formulated into high-quality screen-printable ink based on ethyl cellulose solution in terpineol. The high homogeneity and good adhesion properties of the oxide ink play an important role in obtaining dense and highly crystalline photoabsorber layers. This finding reveals that solution-based screen-printing from readily available oxide precursors provides an interesting cost-effective alternative to current vacuum- and energy-demanding processes of the CIGSe solar cell fabrication.

The utilization of indium sulfide (In₂S₃) photoelectrodes in an all-vanadium photoelectrochemical redox flow battery system has been investigated. The In₂S₃-based photoelectrodes have been prepared via the ultrasonic spray pyrolysis (USP) method. The thickness of the In₂S₃ photoelectrodes has been altered via increasing the pass number of the USP nozzle from 25 to 75 passes. Each pass delivers 6 μL·cm^–2 of the precursor solution. Within the scope of the photoelectrochemical oxidation on the In₂S₃, the vanadium couples of VO²⁺/V³⁺ have been proven to be promising redox species. The maximum charge separation and quantum efficiencies of 46% and 20% have been calculated, respectively.

In this study, we employed zeolitic imidazolate framework-8 (ZIF-8) as the interlayer between the compact TiO₂ and perovskite layers. As a result, enhanced perovskite grain crystallinity, larger grains, and considerably improved photovoltaic performance were achieved in the fabricated perovskite solar cells (PSC). It was demonstrated that the ZIF-8 film includes all characteristics suitable for being applied as scaffold in the PSCs with the advantage of easier synthesis process in room temperature in comparison to the mesoporous TiO₂ counterpart. Moreover, we replaced the thermal annealing process commonly applied on the perovskite layers with room-temperature ultrasonic vibration post-treatment of wet perovskite films.

We report here a molecular phenothiazine-based electrode as a high capacitance and long cycle life (77% retention after 80 000 cycles) pseudocapacitive organic material after hydrothermal deposition on reduced graphene oxide (rGO). Given the high stability of phenothiazine coated rGO hybrid electrodes under positive potentials, pseudocapacitive asymmetric supercapacitors were manufactured using two-dimensional titanium carbide (Ti₃C₂T_x) MXene as the negative electrode, which allowed expansion of the voltage window up to 1.4 V in 3 M H₂SO₄. The optimized asymmetric pseudocapacitors showed capacitance retention of over 80% after 30 000 cycles at 100 mV/s, which is one of the highest for aqueous asymmetric supercapacitors.

We designed semitransparent metagrating supercells that enable control over the spectrum and directivity of incident light for applications in photovoltaics with tailored angular appearance. The building block of the supercells is a 100–120 nm wide and 175 nm tall silicon nanowire that shows a strong Mie resonance around λ = 650 nm. By arranging the resonant Mie scatterers into metagratings of increasing pitch (675–1300 nm), we created a Lambertian-like scattering distribution over an angular range of choice. The millimeter-sized metasurfaces were fabricated using electron beam lithography and reactive ion etching. The fabricated metasurface nearly fully suppresses specular reflection on resonance while 10% of the incoming light around the resonance is scattered into the angular range between 30° and 75°, creating a bright red appearance over this specific range of angles. Off-resonant light in the blue, green, and near-infrared is efficiently transmitted through the metasurface and absorbed in the underlying photovoltaic cell. The implemented silicon heterojunction solar cells with integrated metagrating supercells shows a reduction in external quantum efficiency matching the resonant scattering spectral range. The short circuit current is reduced by 13% due to the combined effects of resonant scattering, reflection from the high-index substrate, and absorption in the Si nanowires. In addition to efficient colorful photovoltaics with tailored angular appearance, the metagrating concept can find application in many other light management designs for photovoltaics and other optoelectronic devices.

In this work, high-performance four-terminal solution-processed tandem solar cells were fabricated by using dye-sensitized solar cells (DSSCs) as top-cells and lead sulfide (PbS) colloidal quantum dot solar cells (CQDSCs) as bottom-cells. For dye-sensitized top-cells, three different dye combinations were used while the titanium dioxide (TiO₂) scattering layer was removed to maximize the transmission. For the PbS bottom-cells, quantum dots with different sizes were compared. Over 12% power conversion efficiency has been achieved by using the XL dye mixture and 890 nm PbS QDs, which shows a significant efficiency enhancement when compared to single DSSC or CQDSC subcells.

Solid electrolytes can be the key for the desired goal of increased safety and specific energies of batteries. On a cell and battery pack level, the all-solid nature and the absence of liquid electrolyte leakage are considered to enable safe and effective performance realization of the rechargeable Li metal electrode and bipolar cell stacking, respectively. Well performing Li metal cells with high-energy/voltage positive electrodes such as LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) can already be cycled when using a blend of the sulfidic solid electrolyte such as β-Li₃PS₄ (LPS) and Li salt in poly(ethylene)oxide (PEO). However, operation of a bipolar stack using these cell materials utilizing the common Al/Cu clad as bipolar plate results in an immediate short circuit, because of an ionic intercell connection via molten LiTFSI/PEO. Oversizing the area of the bipolar plates can prevent such a short circuit and indeed enables a partial charge of the stack, but after a certain time, the next cell failure is observed, consisting of severe, sulfur caused, corrosion of copper which was used as metal substrate for the lithium anode. The exchange of the sulfide incompatible Cu collector by (also area-oversized) stainless steel can finally enable a failure-free performance of the bipolar cell stack, which performs similar to a single cell with regard to cycling stability.

Electrochemical production of hydrogen peroxide (H₂O₂) constitutes a cost-effective and alternative method to the complex and energy-intensive anthraquinone oxidation process. The two-electron water oxidation reaction pathway, while unconventional, is an attractive option for H₂O₂ generation as it can be combined with suitable reduction reactions to effectuate simultaneous electrosynthesis of valuable chemicals at a large scale. In this work we demonstrate that a carbon-based catalyst, boron-doped diamond (BDD), achieves an H₂O₂ concentration and production rate of 29.0 mmol dm^–3 and 19.7 μmol min^–1 cm^–2, respectively, illustrating the capability of BDD as a suitable electrocatalyst for H₂O₂ formation from water.

Magnesium borohydride ammonia borane, Mg(BH₄)₂(NH₃BH₃)₂, was electrochemically investigated. Impedance measurements of the mechanochemically synthesized Mg(BH₄)₂(NH₃BH₃)₂ exhibited an ionic conductivity of 1.3 × 10^–5 S cm^–1 at 30 °C. Electrochemical cells fabricated with Mg(BH₄)₂(NH₃BH₃)₂ as the solid electrolyte demonstrated reversible Mg migration through the material, indicating its potential for use as a Mg ionic conductor in all-solid-state Mg-ion batteries.

In creating the next generation of crystalline silicon (c-Si) solar cells, the goals are to improve energy conversion efficiency and reduce costs. Here, we demonstrate all-room-temperature-processed high-efficiency thin-film/c-Si heterojunction solar cells. Functional thin-film multilayers of ITO/Ni/vanadium oxide (VO_x) and barium oxide (BaO_x)/Al are stacked on the front and rear sides, respectively. The comprehensive analysis revealed Ni and BaO_x interlayers facilitated the selective collection of charge carriers. With the MgF₂ antireflection layer, the efficiency of 17.25% was achieved, suggesting a strategy for the room-temperature fabrication of high-efficiency c-Si solar cells.

A simple-structure zwitterion of sulfamic acid (⁺H₃N–SO₃^–, SA) is introduced to construct an effective chemical bridge between SnO₂ and a perovskite layer through a coordination bond via the -SO₃^– anion for remedying the oxygen vacancies of SnO₂ and meanwhile to passivate charged defects of the perovskite through electrostatic interaction via the -NH₃⁺ cation. The introduced SA results in high-quality perovskite films with large grain size, due to the better wettability for perovskite solution. Consequently, the SA-modified solar cell generates an enhanced efficiency from 18.2% to 20.4% with negligible hysteresis. Remarkably, the unsealed device with SA modification also exhibits considerably improved stability.

Development of a near-infrared (NIR) light-induced hydrogen (H₂) evolution system is indispensable for constructing a sustainable society wherein the utilization of solar energy is maximized. Here, we report NIR light-driven H₂ evolution catalyzed by a combination of a diprotonated saddle-distorted porphyrin as a photosensitizer and platinum nanoparticles as a H₂-evolving catalyst. The quantum yield at 710 nm was determined to be 17%, which is the highest value among photocatalytic H₂-evolution systems ever reported.

Due to the strong electron-withdrawing fluorine groups, the aromatic ring of hexafluorobenzene (HFB) becomes more electron-deficient and strongly interacts with the lone-pair electrons of the medium. When used as an electrolyte additive for Li–S cell, HFB preferably coordinates with low-order lithium sulfides Li₂S and Li₂S₂ and subsequently reacts and converts both into active aromatic sulfides—bis(pentafluorophenyl) disulfides and bis(pentafluorophenyl) polysulfides in situ—thus facilitating the utilization of the electronically insulating Li₂S and Li₂S₂ and improving the cycling stability of the Li–S cell. This research opens a new avenue to tackle the inherent issues associated with the Li–S chemistry.

High κ dielectric/ferroelectric KTaO₃ in the perovskite structure is envisaged here as a host lattice to develop a superior oxide-ion electrolyte. The lossy nature of high κ relaxor dielectricity in KTa_0.4Ti_0.3Ge_0.3O_2.7 was found to result in superior oxide-ion conductivity (σ_o) at elevated temperatures (σ_o > 10^–2 s/cm, T ≥ 550 °C). The maximum of the dielectric constant was found to be ∼5300 at an applied frequency of 20 kHz at 650 °C, and T_m was decreasing with an increasing applied frequency. The high σ_o of KTa_0.4Ti_0.3Ge_0.3O_2.7 was observed in coherence of T_m variation with applied frequency, thus establishing the role of dielectricity/polarization in accelerating the transport of oxide-ion vacancies within the percolation limit inside the host structure.

Phase engineering has a profound effect on the chemical bonding and electric configuration, which play significant roles in regulating the activities of catalysts. The metallic phases of transition-metal dichalcogenides (TMDs) have been proposed to show more excellent performance in electrocatalysis over their semiconductor phase; however, the controllable phase engineering for these compounds remains a challenge. In this work, filmlike 1T′ MoTe₂ (F-1T′ MoTe₂), filmlike 1T′/2H MoTe₂, porous 1T′ MoTe₂, small granular 1T′ MoTe₂, and large granular 1T′ MoTe₂ were successfully synthesized on a flexible carbon cloth (CC) substrate with 3D network structure by chemical vapor deposition (CVD). The high activity of the as-synthesized F-1T′ MoTe₂/CC electrode for HER in 1 M H₂SO₄ solution was demonstrated by the small onset overpotential of −230.7 mV, a low Tafel slope of 127.1 mV dec^–1, and robust electrochemical durability. The enhanced electrocatalytic activity and stability of F-1T′ MoTe₂/CC benefit from excellent catalytically active sites and remarkable conductivity of the F-1T′ MoTe₂. The results demonstrate an efficient route to designing and constructing metallic-phase TMD catalysts for high-performance electrocatalytic devices.

The use of oxide electrolytes promises the safety of Li-ion batteries but complicates the fabrication of electrochemical interfaces. Herein, we report the facile preparation of ionic-transferable interfaces between the electrode and electrolyte in oxide-based bulk-type all-solid-state lithium-ion batteries (ASS-LIBs) owing to the deformability of the LISICON–Li₃BO₃ amorphous oxide, which cannot be realized with currently popular crystalline oxide electrolytes. The amorphous oxide was used to assemble an ASS-LIB even without firing. Moreover, low-temperature heat treatment with a spark-plasma sintering process effectively enhanced the charge–discharge performance of the ASS-LIB: the amorphous oxide was further densified until colorless, and re-formation of a nanosized LISICON crystalline phase in the oxide–electrolyte matrix occurred. The interfacial formability provided by the LISICON–Li₃BO₃ amorphous oxide is an effective route for the successful design of bulk-type oxide-based ASS-LIBs.

Dye-sensitized solar cells (DSSCs) are a strong contender for next-generation photovoltaic technology with niche applications as solar-powered windows. The performance of a DSSC is particularly susceptible to the dye sensitizer, which is adsorbed onto the surface of a wide-band-gap semiconductor such as TiO₂, to form the working electrode. The nature by which such surfaces are sensitized stands to influence the resulting dye···TiO₂ interfacial structure and thence the operational performance of the DSSC working electrode. In particular, a nanoscopic understanding of the sensitization process would ultimately help to improve DSSC device function. In this study, atomic force microscopy (AFM) is used to image the nanoscopic formation of dye···TiO₂ interfacial structures. This employs, as case studies, four well-known DSSC dyes adsorbed onto amorphous TiO₂ substrates: two ruthenium-based dyes, N3 and the Black Dye (N749); and two organic dyes, the thiophenylcarbazole, MK-2, and the zwitterionic squaraine, SQ-2. We discover that all four dyes present some form of aggregation upon sensitization of TiO₂, whose spatial distributions show distinct nanoaggregate particle characteristics. These particle clusters of N749, N3, and MK-2 are found to assemble in lines of nanoaggregates, while clusters of SQ-2 dye chromophores distribute themselves randomly on the amorphous TiO₂ substrates. This nanoparticle structural assembly persists even when these dye···TiO₂ interfaces are fabricated using hundred-fold diluted dye sensitization concentrations. The formation of dye aggregates in N749 is further studied as a function of dye sensitization time. This tracks the pattern formation of aggregates of N749 and reveals that dye aggregation begins within the first hour and has completed within a 5 h period. The large expanse of dye nanoaggregates observed shows that dye···dye interactions are much more important than previously envisaged, while the nature of their spatial distribution can be related to different aggregation modes of the dye molecules. These nanostructural features will undoubtedly impact the performance of DSSCs.

LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) is a highly prospective cathode material for high energy density Li-ion batteries (LIBs). Nevertheless, poor cycling performance and rate capability at high cutoff voltages have dramatically blocked its further commercialization. In this study, an ionic conductive interface has been demonstrated to enhance the NCM electrochemical property at the high cutoff voltage of 4.5 V on account of the existence of a Li-ion conductor of Li₂SnO₃. In comparison to SnO₂, Li₂SnO₃ causes a smoother Li-ion diffusion at the engineered interfaces, lower polarization, slower capacity drop, and voltage fading as well as better H2/H3 reversibility upon cycling. Importantly, it is confirmed that excellent diffusion is beneficial to preservation of reversible phase transition and reduction of polarization, which are directly relative to the superior cyclability and rate capability. This work reveals that building an excellent ionic diffusion interface is feasible for Ni-rich cathodes with simultaneous high capacity and stable cyclability.

Here, a multimodal scanning probe microscopy study of a composite anode with a dispersed lithium silicon titanium phosphate (LSTP) lithium ion conductor for all-solid-state batteries is presented. Using electrochemical strain microscopy (ESM) and lateral force microscopy (LFM), electromechanical response and friction force dependence as a function of the measurement parameters such as the tip loading force and AC drive voltage are analyzed. The sensitivities of friction force and ESM amplitude are found to be valid markers to identify each component in the composite anode. Furthermore, the distribution of active ionic sites of lithium ions is visualized in the comingled region of LSTP and binder materials based on Pearson’s correlation analysis between nanoscale ESM and LFM results. With the suggested technique, various components of composite electrodes can be directly visualized and distinguished in ambient conditions, with their properties being measured simultaneously. These methods will provide insights into the optimal conditions of composite electrodes and allow for developing next-generation all-solid-state batteries.

Bismuth telluride-based alloys are the best-known thermoelectric materials in the room-temperature regime. Here, we report on the enhanced thermoelectric properties of electrodeposited copper-doped tellurium films as an n-type thermoelectric material for near-room-temperature applications. With the increase of the copper content in the films, we observe an enhancement of the thermoelectric properties. Thereby, we investigate the role of copper in modifying the crystal structure, which leads to the amorphous nature of the films and the corresponding enhancement in the thermoelectric properties. The electrodeposited copper-doped tellurium films exhibit a high Seebeck coefficient of −227 μV/K, resulting to a power factor of 5.6 mW/mK², which is a promising power factor observed for the electrodeposited thermoelectric materials and can be a favorable n-type thermoelectric material for device applications.

PEMFCs are an established viable sustainable source of energy, especially for key sectors such as transportation and stationary and portable plants. Pt is their best performing electrocatalyst. However, Pt is affected by stability and durability issues from corrosion, leaching, particle size growth, poisoning, and deleterious byproducts effects. One promising approach to meeting these challenges is the use of metal oxides because of their high chemical and electrical stability. They are usually used in the form of composites or as support materials with some successes but with accompanying challenges of reduced surface area and parts of the surface of the active catalyst NPs still bare, exposing them to some levels of poisoning, leaching, and particle size growth. Hence, in this work Pt@TiO₂ core–shell NPs were prepared, with the surface of the Pt completely covered by TiO₂ to combat these challenges. Uniform size and shape Pt@TiO₂ NPs, with Pt cores of 6.5 nm and TiO₂ shells of 0.5 nm, were obtained using a microemulsion/sol–gel method and hot water treatment, with bare Pt and TiO₂ NPs as controls. Heat treatment at various temperatures showed negligible NP size change up to 300 °C but effective particle size growth suppression by the TiO₂ at ≥400 °C. The NPs showed BET SAs in the order TiO₂ (137) > Pt@TiO₂ (78) > Pt (16.3 m²/g), with their corresponding ECSAs as 0.02, 4.24, and 8.52 m²/g, respectively. A preliminary FC performance evaluation to investigate the feasibility of these NPs as electrocatalysts showed that Pt@TiO₂ had the best performance and stability, compared to even a commercial catalyst, with power generations of 239, 239, and 257 mW/cm² at 150 °C for Pt, Pt@TiO₂, and commercial catalyst, respectively. These results show a significant viable new approach for the application of metal oxides for durable FCs and present new research opportunities.

In the field of photovoltaics, perovskite solar cells have attracted great interest due to their high efficiency combined with a strong potential for low cost and good versatility. One of the main issues concerns the intrinsic stability of these cells. To develop mitigation strategies, there is a critical need for a better understanding of the most plausible degradation mechanisms. This work focuses on the impact of the hole transporting layer (HTL) on the stability of planar NIP perovskite solar cells based on MAPbI_3-xCl_x. From the comparison of two different HTLs (P3HT and PTAA), the crucial role of interfacial materials on the stability of a complete device is demonstrated. Even if PTAA-based devices presented better performances in the initial state, their degradation under mild aging conditions (35 °C, under dark and inert conditions) is more pronounced than that with the P3HT counterpart. Thanks to complementary characterization tools (infrared spectroscopy, X-ray diffraction, UV–visible absorption, and photoluminescence) applied to different stages of the stack assembly (with respectively three, four, or five layers), a degradation mechanism was identified at the perovskite–PTAA interface. These devices consist of several extremely thin layers; the interfaces play an important role on the performances and stability of the complete cells. It is a pioneering work in the community, which could be transposed to other devices and architectures.

The rapid and effective transfer of chemical reactants to solid surfaces through a mesoporous structure is essential for enhancing the catalytic performance of nanomaterials. Such materials are essential for realizing durable, nonprecious-metal-based bifunctional electrocatalysts for rechargeable Zn–air batteries. Herein, highly reactant-accessible and mesoporous ZnMn₂O₄ nanospheres have been prepared via solvothermal synthesis. The nanospheres demonstrate excellent catalytic activity toward the oxygen reduction reaction and the oxygen evolution reaction in an aqueous alkaline solution. Moreover, compared with commercial 20 wt % platinum on carbon black, IrO₂, and RuO₂, the mesoporous ZnMn₂O₄ catalyst exhibits lower charge–discharge voltage gaps, good cycling stability, and improved round-trip efficiency. The enhanced electrochemical performance of the developed catalyst is attributed to the high specific surface area, numerous reaction sites by defective O₂^– (O_ads) species, and sufficient structural stability of the ZnMn₂O₄ material. The achievements presented in this work are of great importance for the development of outstanding non-noble spinel electrocatalysts for Zn–air batteries.

Passivation by small organic compounds can reduce the trap density and enhance the humidity and illumination stability of perovskite solar cells (PSCs). However, the small molecule passivated on the perovskite film cannot endure harsh heat stress. Herein, we find that the trichloro(octyl)silane (TC-silane) is an excellent candidate to modify the perovskite surface and grain boundary nondestructively through the formation of a heat-resistive silicone layer, leading to a comprehensive improvement of efficiency and stability with low cost as well as facile fabrication. The silane is a type of solvent and can be upscaled by a solution process in the device. TC-silicone can cross-link the grain boundaries through hydrolytic condensation. The cross-linking silicone can resist the moisture and heat stresses to enhance the stability. Also, microphotoluminescence reveals that TC-silane treatment can passivate the perovskite film and enhance the optoelectronic properties through chloride replenishment by releasing a hydrogen chloride molecule in the hydrolytic reaction. By utilizing Kevin probe force microscopy, we further uncover that TC-silane forms a dipole layer to facilitate the charge separation. TC-silane passivated PSCs deliver a champion efficiency of 20.03% and remain at 80% of their initial efficiency for more than 800 h at 70–80% relative humidity in air and for about 80 h under 85 °C thermal stress without encapsulation.

The photoanode of a dye-sensitized solar cell is composed of titanium dioxide and a dye adsorbed on the surface. Dye molecules, such as N719 dye, usually agglomerate due to H bond and other factors, forming a multilayer adsorption structure, leading to light loss and electron injection loss. Adding a co-adsorbent to the dye, such as chenodeoxycholic acid (CDCA) molecule, is an effective method to prevent the aggregation of the dye. However, the mechanism of interaction between CDCA and N719 is still unclear. Therefore, in this paper, the mechanism of interaction of CDCA and N719 was studied in detail using quartz crystal microbalance (QCM) combined with UV–vis absorption spectrum. The adsorption kinetics constant of the co-adsorbent CDCA was obtained, and it was found that the adsorption process of CDCA on the surface of TiO₂ was more consistent with the Freundlich isothermal adsorption model. Under the condition of continuous adsorption and desorption, the dynamic constants of CDCA adsorption did not change obviously, but molecular rearrangement might occur. In the process of sequential competitive adsorption, pretreatment with CDCA had a small influence on the adsorption kinetic constants of N719. There is competitive adsorption between CDCA and N719 on the surface of TiO₂. In the process of mixed adsorption, the interaction mechanism between CDCA and N719 is a cooperative mechanism in the solution and competitive mechanism on the TiO₂ surface. In addition, the results of this experiment also showed that CDCA could accelerate the adsorption time of N719. The experimental results in this paper may be helpful for understanding the mechanism of CDCA.

Photovoltaics based on metal halide perovskites have recently achieved a certificated efficiency of 25.2%. One of the factors that limit further development of these devices comes from the defective boundaries between crystalline domains in perovskite solar cells (PSCs). Such boundaries represent a significant loss channel causing nonradiative recombination, but systematic optimization procedures have not been developed yet to control their properties. Herein, we propose a facile but effective defect healing method to passivate the defects along the grain boundaries in PSCs by post-treatment of formamidinium iodide (FAI) solution in isopropyl alcohol (IPA). We use a combination of methods including space-charge-limited current, steady-state and time-resolved photoluminescence, confocal laser scanning microscopy, and transient absorption spectroscopy to show the reduction of density of defect states in perovskite films processed with 1 mg/mL FAI solution. The resultant FAI healed PSCs achieve an average power conversion efficiency of 19.26% (with a champion efficiency of 20.62%), higher than that of 16.45% in the control cell. FAI healed devices without encapsulation maintain nearly 95% of the initial efficiency after 60-day storage under N₂ environment and nearly 78% of the initial efficiency after 30-day storage under the ambient condition with varied humidity. Our results demonstrate that FAI healing is an effective way to passivate the defect states along grain boundaries for high-efficiency and stable PSCs.

The Sn-doped In₂O₃ transparent conductive [indium tin oxide (ITO)] electrode in planar perovskite solar cells (PSCs) is modified by a zirconia (ZrO₂) interlayer with a low-temperature process. Here, the ZrO₂ film is prepared by ultraviolet (UV) treatment at room temperature. The effects of the inserted ZrO₂ interlayer on the performance of CH₃NH₃PbI_3–xCl_x-based PSCs have been systemically studied. After optimizing the process, the champion efficiency of PSCs with a UV-treated ZrO₂ interlayer is 19.48%, which is larger than that of the reference PSC (15.56%). The improved performance in the modified devices is primarily ascribed to the reduced trap states and the suppressed carrier recombination at the ITO/SnO₂ interface. Our work provides a facile route to boost the photovoltaic performance of PSCs by modifying the surface of the transparent conductive electrode at room temperature.

An allylimidazolium-based poly(ionic liquid), poly[vinylbenzylallylimidazolium bis(trifluoromethane)sulfonylimide] (PVBCAImTFSI) was used as a binder for graphite anodes in lithium-ion batteries. The anodes with the synthesized binder exhibited lesser electrolyte degradation and higher lithium-ion diffusion. Electrochemical impedance spectroscopy (EIS) results showed decreased interfacial and diffusion resistance for PVBCAImTFSI-based electrodes after cycling compared to PVDF-based anodes. Dynamic electrochemical impedance spectroscopy (DEIS) results indicated the interfacial resistance of the interface formed for the PVBCAImTFSI-based anodes to be 3 times lesser than the PVDF-based anodes. Suppression of electrolyte degradation and decrease in the intercalation–deintercalation potential and improved Li-ion diffusion coefficient for PVBCAImTFSI-based half-cells were observed from cyclic voltammetry measurements. DFT-based theoretical studies also speculated the suppression in the electrolyte degradation in the case of PVBCAImTFSI binder due to the positioning of its HOMO–LUMO levels. A reversible discharge capacity of 210 mAh/g was obtained for PVBCAImTFSI-based half-cells at 1C rate as compared to the 140 mAh/g obtained for PVDF-based anodic half-cells. After 500 cycles, 95% retention in the discharge capacity was observed. Also, PVBCAImTFSI-based anodes exhibited better charge–discharge stability than the PVDF-based anodes. Suppression of electrolyte degradation, reduction in the interfacial resistance, enhanced wettability, and an optimal SEI layer formed in the case of PVBCAImTFSI-based anodes cumulatively led to an enhanced stability and cyclability during the charge–discharge studies as compared to the commercially employed PVDF-based anodes. Thus, the tuning of the interfacial properties leads to the improvement in the performance of the lithium-ion batteries with PVBCAImTFSI as a binder.

The capability to simultaneously measure changes of mass and charge of electro-active materials during a redox process makes Electrochemical Quartz Crystal Microbalance (EQCM) a powerful technique to monitor stoichiometric changes during reversible electrochemical processes. In principle, quantitative resolution of the stoichiometry of the electro-active sample during electrochemical cycling can be obtained by solving the system of equations for the EQCM mass and charge balance. Such a system of equations couples the measured changes in mass and charge through the stoichiometry of the redox process. Unfortunately, whenever more than two chemically inequivalent species are involved in the redox process, the system of equations is mathematically undetermined, having more variables (stoichiometric coefficients) than equations. In these cases, current best practice is the arbitrary reduction of the number of variables in the mass and charge balance equation, using chemical intuition to set some of the stoichiometric coefficients to fixed values. For layered ion-intercalation host materials, widespread practical approximations are the use of arbitrarily defined solvation numbers for the intercalating ions or the neglect of ion-induced displacement of structural solvent inside the host. Here, we propose an alternative approach based on the use of Density Functional Theory (DFT) to sample and screen, on an energy basis, the whole unreduced spectrum of stoichiometric coefficients compatible with EQCM measurements, leading to DFT energy-assisted resolution of stoichiometric changes during cycling. We illustrate the approach by taking nickel hydroxide Ni(OH)₂ as a case system and studying its ion intercalation-driven phase transformations in the presence of different LiOH, NaOH, and KOH electrolytes. Quantitative resolution of the Ni(OH)₂ stoichiometry during electrochemical cycling unambiguously reveals ion intercalation to displace structural water from the layered host, promoting electrochemical degradation and aging of the material. The process is found to be strongly dependent on the size of the electrolyte cation, with larger cations displacing larger amounts of structural water and resulting in faster degradation rates.

Sequential deposition is one of the most promising approaches toward achieving scalable fabrication of metal halide perovskite thin films. However, this fabrication approach conventionally lends itself to the incomplete conversion of the lead halide, which impacts the stability, performance, and reproducibility of functional devices featuring such thin films. In this work, we have overcome this limitation by using a simple solvent and process engineering approach. We show that through the use of an optimized dimethylformamide and dimethyl sulfoxide solvent mixture in the precursor solution, and through the judicious control of this solution, the substrate, and final annealing temperatures, highly uniform and mesoporous PbI₂ thin films can be deposited. The porous structure of these films is found to accelerate the interdiffusion of CH₃NH₃I (MAI) during the second-step process when carried out at room temperature, enabling their complete conversion into CH₃NH₃PbI₃ perovskite. Detailed investigations using scanning electron microscopy, X-ray diffraction, grazing-incidence wide-angle X-ray scattering, thermogravimetric analysis, UV–vis absorption, photoluminescence, and time-of-flight secondary ion mass spectrometry have been used to provide mechanistic insights into the porous PbI₂ film formation and the interdiffusion process. Solar cells based on planar fluorine-doped tin oxide (FTO)/TiO₂/CH₃NH₃PbI₃/spiro-OMeTAD/Au device architectures yield optimized device efficiencies of 19%, which is among the highest for this device structure and perovskite absorber material. The applicability of this enhanced sequential deposition method to other perovskite systems has been further validated through the fabrication of efficient FA_xMA_1–xPbI_xBr_3–x and CsPbI_xBr_3–x solar cells.

The nickel-rich transition metal oxide—NMC, LiNi_1–x–yM_xCo_yO₂, 1 – x – y ≥ 0.6—shows great potential for use in lithium-ion batteries that exhibit high energy densities; however, large-scale use of the material in batteries is hindered by technical challenges, including secondary particle cracking, interfacial instability, and cell degassing during cycling. In this paper, we report a strategy that employs minimal Al doping to improve the bulk integrity, structure, and interfacial stability of the cathode and, hence, the long-term cycling capability. With only 1 mol % Al doping, the Al-NMC76 electrode can retain 79.2% capacity after 500 cycles at 4.5 V, which is far better than the capacity retention for undoped NMC76 tested under similar conditions. The improved cycling can be attributed to the Al doping in the NMC76, which not only improves bulk structural stability by introducing the Al doping into the lattice but also suppresses chemical reactions with the acidic electrolyte.

Solar-driven evaporation is a promising technology with many potential applications including desalination, power generation, purification, sterilization, and phase separation. Recently, much research has been directed toward increasing solar-driven evaporation efficiencies with photothermal materials that reside at the air–water interface to provide a localized thermal energy source when subjected to solar radiation. In this work, composite foams of carbon nanoparticles (CNPs) and polydimethylsiloxane (PDMS) were fabricated by a facile salt-leaching technique and used as interfacial receivers for solar evaporation. The inclusion of CNPs significantly increases the solar absorptivity of the foams to ∼97% without impacting their inherently low thermal conductivity. Polyvinyl alcohol (PVA) modification was applied to endow the foams with hydrophilicity, thereby enabling continuous water transport to the air–water interface. An enhanced water evaporation rate of 1.26 kg/m²·h with a solar-to-evaporation efficiency of 80% was achieved under a relatively low solar input of 850 W/m². With their simple structure and excellent photothermal performance, the PVA-CNP/PDMS foams are promising candidates for solar evaporation applications.

The major cause for capacity fading of silicon nanoparticle (SiNP)-based electrodes is the immense pressure applied toward the conductive networks during the charge/discharge process. While numerous efforts have been devoted to investigating different types of polymer binders, the rational design of an adhesive binder with pressure sensitivity has rarely been reported. Herein, a series of pressure-sensitive adhesives (PSAs) synthesized via copolymerization of 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA) are evaluated as polymer binders for SiNP-based electrodes. The balance between the density of interaction groups and viscoelastic properties is systematically investigated for efficient binding performance. The SiNP-based electrode using PSA with 20 mol % of 2-EHA (Si-PSA-20%) exhibits excellent electrochemical performance, achieving a capacity retention of 83% at the 100th cycle compared with 54% for Si-PAA after activation. Si-PSA-20% also delivers a superior cycling performance at a high current density (1731 mAh g^–1 after 350 cycles vs 719 mAh g^–1 after 150 cycles for Si-PAA, 1.8 A g^–1) and at high mass loading of active materials (capacity retention of 74 vs 38% for Si-PAA after 100 cycles, SiNP content ∼1.2 mg cm^–2). Atomic force microscopy (AFM), peel tests, and Car–Parrinello molecular dynamics (CPMD) simulations are employed to understand their binder performance. The novel design and systematical investigation of PSAs as binders will definitely be appealing for not only the Si electrode but also for other high-energy-density electrode materials.

Porous carbon nanoparticles (PCNs) co-doped with nitrogen and sulfur have been produced by applying a straightforward template-free method entailing a high-temperature reaction between polypyrrole nanoparticles and sodium thiosulfate. The activation process gives rise to porous carbon nanoparticles that combine several important properties: (a) a uniform size of ∼80 nm; (b) a well-developed porosity with BET surface areas of up to ∼1700 m² g^–1 and pore volumes of up to 2.20 cm³ g^–1; (c) a sizable N and S heteroatom content (of up to 2.7% N and 7.7% S); and (d) a good electrical conductivity (up to 3 S cm^–1). The synthesis strategy offers a great versatility since two types of materials, PCN or S/PCN (nanocomposites comprising elemental sulfur infiltrated into the PCN), can be produced by introducing minor changes to the procedure. These materials have been tested on two components of a lithium–sulfur cell. The S/PCN nanocomposite is used as the cathode, whereas the PCN material is deposited onto the separator to form a thin packed layer in order to restrict the mobility of the polysulfides. Remarkably, the PCN coating layer notably enhances the utilization of sulfur (increase of 23% during the first cycles), and it provides robustness during long-term cycling. The battery assembled with these two components exhibits a highly stable cycling performance from the very first charge–discharge cycles and delivers a reversible capacity of 841 mAh g^–1 after 100 cycles at 0.2C with a Coulombic efficiency of 99.3%. Despite using a S/PCN composite with a high sulfur content (>70%), the cell was successfully cycled at 2C over 500 charge–discharge cycles and experienced a capacity decay of only 0.089% per cycle.

In this work, the molybdenum oxide (MoO_x) was employed as a back contact layer to improve the device performance of ultrathin Cu(In,Ga)Se₂ (CIGS) solar cells with CIGS absorber synthesized through the low-temperature three-stage co-evaporation process. This contribution focuses on the investigation of the inherent mechanisms and the improved device performance in detail. Our research shows that the energy band of the CIGS/Mo interface can be tuned and the Schottky barrier can be reduced. Compared with the reference sample without MoO_x, the back barrier height of the new device with 10 nm MoO_x enjoys a significant decrease from 43.83 to 15.98 meV because of the improvement of energy band structure. Meanwhile, the results of wxAMPS simulation corroborate that the energy band bends upward in the devices with an appropriate thickness of MoO_x films, which facilitates the carrier transportation and suppresses the recombination of charge carriers at the MoO_x/Cu(In,Ga)Se₂ interface. Moreover, the carriers can transport through the MoO_x/CIGS interface by tunneling when the MoO_x film is thin enough. Finally, by controlling the thicknesses of MoO_x films, an efficiency of 10.38% is achieved in 0.5 μm CIGS solar cells by optimizing the MoO_x thickness under the low-temperature three-stage co-evaporation process.

Garnet-type lithium lanthanum zirconate (Li₇La₃Zr₂O₁₂, LLZO)-based ceramic electrolyte has potential for further development of all-solid-state energy storage technologies including Li metal batteries as well as Li–S and Li–O₂ chemistries. The essential prerequisites such as LLZO’s compactness, stability, and ionic conductivity for this development are nearly achievable via the solid-state reaction route (SSR) at high temperatures, but it involves a trade-off between LLZO’s caveats because of Li loss via volatilization. For example, SSR between lithium carbonate, lanthanum oxide, and zirconium oxide is typically supplemented by dopants (e.g., gallium or aluminum) to yield the stabilized cubic phase (c-LLZO) that is characterized by ionic conductivity an order of magnitude higher than the other polymorphs of LLZO. While the addition of dopants as phase stabilizing agent and supplying extra Li precursor for compensating Li loss at high temperatures become common practice in the solid-state process of LLZO, the exact role of dopants and stabilization pathway is still poorly understood, which leads to several manufacturing issues. By following LLZO’s chemical phase evolution in relation to Li loss at high temperatures, we here show that stabilized c-LLZO can directly be achieved by an in situ control of lithium loss during SSR and without needing dopants. In light of this, we demonstrate that dopants in the conventional SSR route also play a similar role, i.e., making more accessible Li to the formation and phase stabilization of c-LLZO, as revealed by our in situ X-ray diffraction analysis. Further microscopic (STEM, EDXS, and EELS) analysis of the samples obtained under various SSR conditions provides insights into LLZO phase behavior. Our study can contribute to the development of more reliable solid-state manufacturing routes to Garnet-type ceramic electrolytes in preferred polymorphs exhibiting high ionic conductivity and stability for all-solid-state energy storage.

This article reports the first instance of exploring a chemically Zn(II) preinserted organic–inorganic hybrid material [vanadyl ethylene glycolate or VEG, (VO(CH₂O)₂)] as an efficient cathode for rechargeable zinc-ion batteries (ZIBs). The control VEG electrode synthesized by a glycothermal process showed a modest specific capacity of 157 mAh/g at 0.1 A/g current density, however, suffered from poor rate capability and cycle stability due to structural dissolution. Chemically Zn(II) preinsertion into VEG (Zn-VEG) catalyzed the Zn²⁺ intercalation in the Zn-VEG cathode with a significantly decreased charge transfer resistance, resulting in high discharge capacity of 217 mAh/g (at 0.1 A/g) accompanied by excellent rate capability with ∼50% capacity retention on increasing the current by 50 times. A first-principles-based hybrid density-functional theory (DFT) study revealed that the electronic structure of the Zn-intercalated VEG is thermodynamically stable, indicating an energetically favorable Zn-ion intercalation process. The Zn(II) preinserted VEG cathode allowed faster ionic diffusion (D_Zn²⁺ in the order of 10^–9 cm²/s), and the diffusion controlled process was the major contributor (∼66.9%) to the overall capacity at low scan rate (0.1 mV/s) and remained significant (43.8%) even at high scan rate of 0.8 mV/s. Furthermore, the Zn(II) preinsertion in the VEG could act as a bridge to hold the VEG layers firmly. This provides the desired structural stability to the Zn-VEG cathode during a continuous Zn²⁺ insertion/deinsertion process, resulting in excellent cycle stability with only ∼0.005% capacity loss per cycle over 2000 cycles (at 4 A/g) while maintaining a high columbic efficiency of 99.9% throughout the cycles. The high capacity accompanied by excellent rate capability and cycle stability supports the as-prepared Zn(II) preinserted organo-vanadyl hybrid electrode to be a potential cathode material for ZIBs.

Porous and hollow nanomaterials have been an exciting research area for numerous next-generation technological applications. However, it is still a challenge to assemble porous and hollow nanostructures of appropriate composition and characteristics in designed architectures. Here, we report a self-templated metal–organic frameworks based strategy for the synthesis and engineering of porous and hollow nanostructures in designed architectures by developing graphitic-carbon-intermingled porous Co₃O₄ nanotentacles, for the first time, on electrospun hollow carbon nanofibers in a designed 3D pattern (3D Co₃O₄/C@HCNFs). The as-developed nanocomposite sheet, as a free-standing electrode for supercapacitors, shows a high specific capacity of 199 mA h g^–1 (1623 F g^–1) at 1 A g^–1 with good cyclic life and outstanding rate capability. Moreover, the assembled asymmetric supercapacitor device supplies an energy density of 36.6 W h kg^–1 at the power density of 471 W kg^–1 with significant cyclic life and rate capability indicating its potential practical application. This synthetic strategy suggests a simple, cost-effective and convenient route for the synthesis and assembly of porous and hollow structured nanomaterials in designed architectures for diverse applications.

The integration of III–V materials with crystalline Si (c-Si) is a promising pathway to design high-performance optoelectronic devices, including solar cells. We have previously reported high-efficiency III–V/Si tandem cells using our unique semiconductor bonding technique, termed smart stack. In the conventional smart stack cells, Pd nanoparticle (NP) arrays have been commonly employed as bonding mediators between III–V and c-Si; however, from an economical point of view, the use of other low-cost metals would be preferable. Therefore, this study focused on the possibility of Cu. A polystyrene-block-poly-2-vinylpyridine (PS-b-P2VP)-based block copolymer was utilized to prepare Cu NP arrays. Desired Cu NP arrays were achieved by starting with self-assembled PS-b-P2VP micelles preloaded with Cu²⁺ ions. Satisfying bonding properties (low-resistance interfaces) were confirmed when GaAs subcells were stacked on the Cu NP arrays formed on native-oxide-removed c-Si subcells. Conversion efficiencies of up to 25.9% have been demonstrated with triple-junction structures consisting of InGaP/GaAs top and c-Si bottom subcells. The long-term reliability of Cu NP array-mediated smart stack cells was also verified by the thermal cycle and damp heat tests. Hence, we have successfully confirmed that not only Pd but also Cu is available to realize high-efficiency smart stack cells.

Solid-state supercapacitors have never been able to compete with their liquid electrolyte counterparts, forming a major impediment for their utilization in portable and wearable electronics. Attempts to improve the rate capability of solid-state supercapacitors have predominantly focused on the morphology or porosity of the electrode material, and largely ignored the critical role of electrolyte. Here, we report the fabrication of a carbon nanotube yarn (CNT-yarn) based flexible all-solid-state coaxial-type supercapacitor operable at scan rates as high as 250 000 mV/s, exhibiting high energy (6.2 mWh/cm³) and power density (4465 mW/cm³). Electrode–electrolyte interfacial resistance is lowered by 28.3% to achieve ultrafast frequency response (τ = 3.2 ms) through thermal engineering of the CNT-yarn–polymer electrolyte interface. This creates synergistic chemical functionality on the CNT-yarn and simultaneous diffusional broadening of the electrode–electrolyte interface, as revealed by micro-Raman spectral mapping, and accounts for both the high rate capability and high energy density. High Columbic efficiency (∼98%) and extremely low iR_drop (<5%) that is unprecedented among solid-state supercapacitors are direct implications of such thermal interfacial engineering. Furthermore, the coaxial device is mechanically tenacious and bendable up to 360°, with superior cyclability (95% for 10000 cycles) as demonstrated by its seamless integration on to wearable platforms.

Cubic cuprous oxide is applied in the selective catalytic oxidation of ammonia to nitrogen (NH₃-SCO) to investigate the effect of structure evolution on catalytic performance. Different structures (Cu₂O, Cu₂O–CuO, and CuO) that formed progressively during the reconstruction process with time are discovered by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and other characterization methods. The optimal CuO–Cu₂O exhibits the best catalytic performance, which has T_100% = 210 °C and above 80% N₂ selectivity. Combining the experimental method and the density functional theory (DFT), the oxygen molecule is adsorbed in the form of a stable molecular state on Cu₂O particles, while the dissociative adsorption of O₂ occurs over the mixed CuO–Cu₂O and pure CuO phases. It is found that O₂ is more likely to be dissociated and activated on CuO–Cu₂O with E_ads = −7.15 eV. There are three kinds of intermediate species (monodentate, bidentate, and bridging nitrate) observed. The formation of key bidentate nitrate species facilitates NH₃ conversion and N₂ formation, but the other intermediate species have a negative effect on NH₃ oxidation.

Developing sodium (Na)-ion batteries is highly appealing because they offer the potential to be made from raw materials, which hold the promise to be less expensive, less toxic, and at the same time more abundant compared to state-of-the-art lithium (Li)-ion batteries. In this work, the Na-ion storage capability of nanostructured organic–inorganic polyaniline (PANI) titanium dioxide (TiO₂) composite electrodes is studied. Self-organized, carbon-coated, and oxygen-deficient anatase TiO_2–x-C nanotubes (NTs) are fabricated by a facile one-step anodic oxidation process followed by annealing at high temperatures in an argon–acetylene mixture. Subsequent electropolymerization of a thin film of PANI results in the fabrication of highly conductive and well-ordered, nanostructured organic–inorganic polyaniline-TiO₂ composite electrodes. As a result, the PANI-coated TiO_2–x-C NT composite electrodes exhibit higher Na storage capacities, significantly better capacity retention, advanced rate capability, and better Coulombic efficiencies compared to PANI-coated Ti metal and uncoated TiO_2–x-C NTs for all current rates (C-rates) investigated.

Interface engineering of metal and semiconductive spinel oxides is an efficient approach to improve conductivity and ultimately boosting electrocatalytic property. Herein, we present the synthesis of Cu-CuFe₂O₄ nanohybrid coupled with conductive carbon (Cu-CuFe₂O₄/C) as a highly efficient electrocatalyst for oxygen reduction reaction (ORR). The metallic Cu and semiconductive oxide CuFe₂O₄ interface provides better electronic conductivity, and carbon matrix offers conductive support for electron/ion transfer process. Consequently, the Cu-CuFe₂O₄/C electrode exhibits superior current density (4.35 mA cm^–2) in comparison to the standard Pt/C (3.81 mA cm^–2) along with other catalyst systems toward ORR. Thus, the nanohybrid that combines the advantages of metallic Cu and chemical interaction of carbon matrix along with its magnetic behavior establishes remarkable enhancement in ORR activity. Furthermore, it also exhibits superior mechanical and electrochemical stability compared to that of Pt/C. Thus, the unique structural design offers a new approach for the fabrication of magnetic metal-oxides electrodes with enhanced ORR performance via interface engineering.

We report on thermally stable inorganic mixed halide perovskite solar cells deposited using a vapor deposition technique with no loss in device performance at 200 °C for 72 h. X-ray diffraction analysis confirms no compositional degradation of the perovskite layer up to 200 °C anneals. We use a layer-by-layer vapor deposition technique with thin layers (several nanometers) of PbI₂ and CsBr precursors to fabricate inorganic mixed halide perovskite solar cells with a photoconversion efficiency of 11.8%. We study the effect of several key parameters of the perovskite fabrication process that control the intermixing of the perovskite layer and their effect on device efficiency and hysteresis. The thermal stability of the perovskite material and its energy band gap of 1.87 eV makes it appropriate for use in tandem junction cells for use in real-life environments with high solar illuminance where the ambient temperatures exceed 55 °C in the summer, and silicon cell module temperatures approach 86 °C.

Choline chloride as a photosynthesis promoter is important for increasing plant yield, and we have found that it has a similar effect in perovskite solar cells (PSCs). Here, we propose the innovation of using molecular self-assembly methods to produce a choline chloride monolayer on the surface of the SnO₂; this monolayer works as a passivation layer that reduces the surface oxygen vacancies and improves the performance of CH₃NH₃PbI₃ (MAPbI₃) PSCs. The MAPbI₃ PSC based on SnO₂ modified by choline chloride (Chol-SnO₂) electron transport layer (ETL) achieves an optimal power conversion efficiency (PCE) of 18.90% under one solar illumination. The PCE is increased by 10–25% compared to the device without modification, and hysteresis is significantly reduced by eliminating the charge accumulation between the interface of the perovskite and ETL. More importantly, the MAPbI₃ PSC based on Chol-SnO₂ ETL exhibits a higher open-circuit voltage (V_OC) of 1.145 V compared to the control device (1.071 V). This work provides a very simple and effective way to improve PSC performance, which has long-term significance for the sustainable development of energy.

Porous catalysts with a higher activated surface area are strategic materials to enhance the oxygen reduction reaction (ORR) and improve the performance of the microbial fuel cells (MFCs). In this investigation, a highly porous cagelike zirconium metal–organic framework (Zr-MOF) was synthesized by the solvothermal method and used as the ORR catalyst in an air-cathode MFC. Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy revealed the successful synthesis of Zr-MOF having a high specific surface area of 858 m²/g. Cyclic voltammetry analysis demonstrated a sharp ORR peak current at −0.38 V having a current value of 11 mA compared to the negligible amount of peak current observed for cathode having no catalyst. The MFC having Zr-MOF-catalyzed cathode could translate a power density of 131.2 ± 3.5 mW/m² at a coulombic efficiency of 29.04 ± 1.54% from the organic matter present in wastewater; these values were comparable with the MFC having 10% Pt/C on cathode (128.7 ± 4.9 mW/m² and 29.03 ± 2.76%, respectively). The cost of energy production by the Zr-MOF cathode was estimated to be ca. 4.4 times lower than that by the 10% Pt/C cathode. The performance of MFC indicates that Zr-MOF could be an excellent alternative cathode catalyst, to the costly Pt/C, upon ambitious scale-up of MFCs.

Perovskite solar cells (PSCs) have developed rapidly in the past 10 years. However, they are faced with a huge challenge for stability improvement because of the volatile organic components in the light absorption and hole transporting layer. Herein, we fabricate all-inorganic PSCs with the structure of FTO/c-TiO₂/m-TiO₂/CsPbI₃ quantum dots (QDs)/Cu₁₂Sb₄S₁₃ QDs/Au to improve device stability. To enhance the photovoltaic performance of PSCs, the surface oleylamine ligands of Cu₁₂Sb₄S₁₃ QDs with 3-mercaptopropionic acid are exchanged, as the enhanced electronic coupling and reduced band gap are realized after the ligands exchange. Cu₁₂Sb₄S₁₃ QD based PSCs exhibit a PCE of 10.02%, approaching that of the spiro-MeOTAD based PSCs (12.14%). A high short-circuit current density of 18.28 mA cm^–2 is achieved because of the enhanced light absorption and excellent hole extraction ability of Cu₁₂Sb₄S₁₃ QDs. Moreover, Cu₁₂Sb₄S₁₃ QD based PSCs exhibit the improved long-term stability and retain 94% of their initial PCE after storage in ambient air for 360 h.

Energy storage devices such as supercapacitors of high performance are in great need due to the continuous expansion of digitalization and related devices for mobile electronics, autonomous sensors, and vehicles of different kinds. However, the nonrenewable resources and often complex preparation processes associated with electrode materials and structures pose limited scale-up in production and difficulties in versatile utilization of the devices. Here, free-standing and flexible carbon nanofiber networks derived from renewable and abundant bioresources are demonstrated. By a simple optimization of carbonization, the carbon nanofiber networks reach a large surface area of 1670 m² g^–1 and excellent specific gravimetric capacitance of ∼240 F g^–1, outperforming many other nanostructured carbon, activated carbon, and even those decorated with metal oxides. The remarkable electrochemical performance and flexibility of the green carbon networks enable an all-solid-state supercapacitor device, which displays a device capacitance of 60.4 F g^–1 with a corresponding gravimetric energy density of 8.4 Wh kg^–1 while maintaining good mechanical properties.

The polysulfide shuttle effect has remained one of the main obstacles restraining the commercialization of lithium–sulfur battery technology. Herein, we report a yolk–shell structure with nickel disulfide nanoparticles encapsulated in the chemical vapor deposition (CVD)-grown N-doped graphene (NG) nanoshell (termed as NiS₂@NG). The synthesis process involves the growth of NG nanoshells simply by annealing Ni nanoparticles in soybean oil vapors without compressed gases, followed by solid-state sulfidation of partially etched Ni nanoparticles. Benefiting from both the physical and chemical confinement mechanisms, the NiS₂@NG material exhibits exceptional lithium polysulfide (LiPS) trapping competence (even within a few seconds), as evidenced by visual adsorption and X-ray photoelectron spectroscopy (XPS) analyses. The NiS₂@NG cathode demonstrates excellent specific capacity (1213 mA h g^–1 at 0.2C current density), good rate capability (by retaining 782 mA h g^–1 capacity at 2C current density), and outstanding cycling stability (78% after 100 cycles at 0.5C current density). Moreover, a high sulfur content of 90% is realized with good cycling stability. Besides this, hollow NG nanoshells loaded with sulfur (NG@S) exhibited comparable electrochemical performance but bare NiS₂ showed sluggish redox kinetics and poor electrochemical performance due to poor electrical conductivity and the absence of physical confinements. The findings of this study are strongly believed to open up pathways for the development of cathode materials for Li–S batteries.

Simultaneous realization of superior energy density and cyclic stability of a cathode material under high rate is imperative for practical applications in rechargeable lithium-ion batteries (LIBs). In the present work, the effects of a marginal amount of K substitution of Li on the electrochemical properties of the Li_1–xK_xV_0.98Nb_0.02PO₄F@C (L_1–xK_xVNPF@C, x = 0–0.01) cathode materials are investigated. As a result, K substitution of Li has a great influence on the electronic conductivities, ionic conductivities, charge transfer resistances, and Li⁺ diffusion coefficients of the L_1–xK_xVNPF@C (x = 0.003–0.01) cathode materials. Substantially improved discharge capacities and energy densities are observed in the L_1–xK_xVNPF@C (x = 0.003–0.01) cathodes under high charge/discharge current densities of 0.4–1 A g^–1. In particular, because of the highest Li⁺ conductivity and diffusivity, the L_0.995K_0.005VNPF@C cathode exhibits an optimal electrochemical performance at both 25 and 50 °C. It delivers a high discharge capacity of 101 mA h g^–1 at 10 C with a capacity retention of 95.3% after 1000 cycles at 25 °C. Correspondingly, the initial discharge energy density and energy retention is 396.2 Wh kg^–1 and 96.4%, respectively. Even evaluated at 9 C and 50 °C, the initial discharge energy density and energy retention after 500 cycles is 420.6 Wh kg^–1 and 92.9%, respectively, which is highly promising for practical applications. The present work may provide a valuable guidance to elevate the energy density and cyclic stability of a cathode material for high-rate LIBs.

Nonstoichiometric silica suboxides (SiO_x) have been regularly investigated as hopeful anode materials for the substitutions of silicon. However, the inherently poor conductivity of SiO_x limits its promotion in industry. Herein, for the propose of enhanced conductivity and stability of SiO_x-based materials, a kind of multicomponent nanosheet (rGO@SiO_x@C) is designed and fabricated successfully. This progressive design consists of inner nanosheet substrate from reduced graphene oxide (rGO), an intermediate layer of SiO_x, and a nitrogen-doped nanoporous carbon (NNC) shell from the pyrolysis of poly(vinylpyrrolidone). More importantly, the controllable pore structure is introduced into this two-dimensional nanostructure, accommodating volumetric change of SiO_x during the charging/discharging process. Benefiting from unique structural advantages, the as-prepared rGO@SiO_x@C nanosheets exhibit excellent electrochemical properties, such as high rate performance and stable long lifetime. We anticipate that this approach to enhance the conductivity and stability of SiO_x-based anode materials has potential applications for future sustainable development in lithium-ion batteries.

Photoelectrochemical (PEC) water splitting is one of the most promising green technologies for producing renewable clean hydrogen energy. Developing plasmonic semiconductors with tunable plasmonic resonance to visible light has drawn increasing attention in view of utilizing abundant low-energy photons for solar-to-chemical conversion. Herein, we demonstrate for the first time that the WO₃ electrode can be partly reduced by various metal foils in acid solution, showing strong localized surface plasmon resonance (LSPR) in the visible-to-near-infrared (vis–NIR) region. The LSPR can be precisely tuned using metal foils with different standard electrode potentials for different reaction times, and the LSPR peak position strongly depends on the concentration of W⁵⁺ in the WO_3–x electrodes. A photocurrent density of 0.79 mA·cm^–2 at 1.23 V_RHE, which is twice that of pristine one, is obtained over an optimally reduced WO_3–x electrode. The enhanced PEC water splitting performance is ascribed to the increased light absorption, conductivity, and charge-carrier concentration.

The slow kinetics of oxygen evolution reaction (OER) catalysts with a large overpotential restricts the feasibility of electrochemical water splitting. Iron based electrodes are attractive candidates, but elevating their activity faces great challenges in weak intermediate adsorption. Herein, we demonstrated that ultrathin FeP nanosheets with Fe defects on nickel foam (FeP-NS/NF) exhibited a remarkable electrocatalytic oxygen evolution performance. The overpotential of FeP-NS/NF only requires 220 mV to achieve a current density of 10 mA cm^–2 in 1 M KOH solution. Moreover, it possessed excellent durability during the 85 h stability test. Fe defects over ultrathin FeP evidenced by X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) have been experimentally demonstrated to promote oxygenated intermediate adsorption, which largely reduce the overpotential of OER.

The lithium/sulfur batteries are of significant interest because of their potential use in next-generation energy storage. After years of efforts, the bottleneck in their application still remains to be the polysulfide dissolution and thus induced impact on the cathode itself, the electrolyte, and the Li anode. In this work, in situ 1,3-dioxolane (DOL) polymerization initiated by the poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) co-polymer is proposed and further introduced into the Li/S cell by a piece of the dual-function PEDOT:PSS film. The synergistic effect of PSS and PEDOT is revealed and their roles are investigated. With the PEDOT:PSS film and single DOL solvent electrolyte, the quasi-solid-state electrolyte is in situ formed within the cell and in turn leads to a 840 mA h/g capacity after 100 cycles, accompanied with a constant efficiency of ∼99%. The work sheds more light on the in situ polymerization technique and provides a comprehensive approach for solving the issues of Li/S cells.

Silk fibroin (SF) is recognized for its rich nitrogen content and has been explored for its promising potential in energy storage because of its hexagonal pseudographitic structure from the direct transformation of the unique secondary protein β-sheet peptides of carbonized SF. In this work, we proposed a novel strategy that combined with in situ electrophoresis and electrogelation of SF as well as the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) for producing high-level nitrogen-doped (N-doped) carbons. A high β-sheet content of SF can be synthesized in a three-dimensional (3D) inverse opaline skeleton via double-network microstructure (physical β-sheet cross-linking and chemical PEDOT cross-linking) induced by the hydrophobic EDOTs. This synergistic effect regulating SF distribution and balancing the intra/intermolecular hydrogen bonding among SF results in boosting β-sheet contents. Herein, this 3D SF/PEDOT composite inverse opal (SPIO) exhibits a much ultrahigh-concentrated β-sheets (46.4%) compared to pure electrogelated SFIO with 16.4% of β-sheets. After subsequent pyrolysis, a high-level (14.7%) N-doped pseudographitic carbon inverse opal is realized. For evaluation as a pseudocapacitor, this high-level N-doped pseudographitic carbon inverse opal shows a capacitance of 342 F g^–1 at 0.5 A g^–1 and a commendable energy density of 31.7 Wh kg^–1 at an ultrahigh power density of 25009 W kg^–1 (at 50 A g^–1). After galvanostatic charging/discharging at 15 A g^–1 for 10000 cycles, the sample maintains an impressive capacitance retention of 89.8%.

We present in this paper a modification and stabilization approach for the surface of a high specific capacity Ni-rich cathode material LiNi_0.85Co_0.10Mn_0.05O₂ (NCM85) via SO₂ gas treatment at 250–400 °C, in order to enhance its electrochemical performance in advanced lithium-ion batteries. It was established that SO₂ interactions with NCM85 result in the formation of a nanometer-sized Li₂SO₄ surface layer on the oxide particles with no impact on the bulk structure of the material and its morphology. We consider the above interactions as oxidation–reduction processes resulting in direct oxidation of sulfur and partial reduction of Ni³⁺ as revealed by high-resolution XPS and electron paramagnetic resonance studies. The important impacts of the SO₂ treatment are a remarkably stable cycling performance of cathodes comprising this material with ∼10% increase in capacity retention and lesser voltage hysteresis upon cycling compared to untreated NCM85 cathodes. The SO₂-treated NCM85 material is also significantly thermally stable, demonstrating lower heat evolution upon thermal reactions with standard EC-EMC/LiPF₆ solutions by 12–20%, compared to untreated material. The proposed approach to modify the surface of Ni-rich NCM cathode materials by SO₂ treatment is demonstrated to be a promising method to enhance their electrochemical performance. This work demonstrates a leap in performance of Ni-rich NCM cathode materials by increasing the content of nickel compared to any benchmark cathodes and is a promising approach for stabilization by surface modification.

Hierarchical architecture of porous anatase TiO₂ microspheres is obtained by a universal solvothermal reaction, which can improve the cycling stability and ionic/electronic transport properties in sodium-ion batteries without further coating, carbon modification, or element doping. Meanwhile, through combining the porous structure with an ether-based electrolyte, the electrochemical properties of this material have been significantly enhanced. A great specific capacity of 207.3 mA h g^–1 at 1 C (168 mA g^–1) after 250 cycles can be achieved. Even at an unimaginable current density of 40 C, an outstanding cycle life was achieved with a capacity of 140.6 mA h g^–1 over 10000 cycles. Furthermore, in situ Raman spectroscopy and ex situ XRD pattern analyses were carried out to explore the structural transformation in the first cycling process.

We investigated the thermoelectric transport properties of InTe_1−δ (δ = 0.0, 0.1, and 0.2) compounds and interpreted their unusual behavior in terms of electronic and phonon band dispersions. The temperature-dependent electrical resistivity ρ(T) and Seebeck coefficient S(T) exhibit the charge density wave (CDW) transition near 87 K for InTe_1−δ (δ = 0.1 and 0.2) compounds. The CDW transitions on the Te-deficient compounds can be supported by the Fermi surface nesting along the M–X line in InTe_1−δ (δ = 0.25). The temperature-dependent Hall carrier density n_H shows unusual behavior in that the n_H(T) is increased by the Fermi surface reconstruction. From the temperature-dependent X-ray diffraction measurements, we found the superstructural lattice distortion at low temperatures (T ≤ 175 K), implying the intrinsic lattice instability. During the structural phase transition from tetragonal (I4/mcm) or orthorhombic (Ibam) to superstructural orthorhombic (Pbca) in InTe and Te-deficient InTe_0.8, we observed a negative thermal expansion coefficient, giving rise to the large variation of negative Grüneisen parameters. Owing to the significant change in thermal expansion coefficients and Grüneisen parameters with respect to temperature, the energy band structure, in other words, Fermi surface, depends on the temperature, indicating a temperature-driven Lifshitz transition in InTe_1−δ compounds. The Te-deficiency induces significant anharmonicity of phonons from the numerous flat bands and negative phonon branches. The coexistences of temperature-driven Lifshitz transition, CDW formation, and lattice anharmonicity with high negative Grüneisen parameter in InTe_1−δ are very exceptional cases and suggest the profound physical properties in the compounds.

Advances in lithium-ion batteries (LIBs) have enabled the realization of lightweight power sources with high energy density, specific capacity, and cyclic stability. As LIBs are inherently subjected to thermomechanical stress during operation, their volume change can be indicative of their electrochemical reactions and safety status. In this study, a carbon nanotube (CNT)-based dilatometer that is stretchable and can be conformally mounted on the surface of LIBs has been developed for sensitive and in situ measurements of the LIB swelling. The CNTs form a percolation network on top of a thin elastomer and exhibit a positive gauge factor of ∼50 and a negative temperature coefficient of resistance of −0.075% K^–1, enabling a quantitative extraction of the extent of swelling. As a result, both regular (∼50 μm swelling by lithiation/delithiation cycles) and irregular (a few millimeter swelling by abnormal gas evolution because of increased temperature) reactions of LIBs are successfully detected in real time. Unlike the conventional dilatometers that are complex, expensive, and bulky, the CNT sensor, because of its simplicity, portability, and sensitivity, is useful for understanding electrochemical reactions and preventing serious failures of portable LIBs, without disassembling them from the other components of the device.

The oxygen reduction reaction (ORR) is critically important in energy converting systems, and the advancement of a catalyst that accelerates the process is vital. Here, an ORR electrocatalyst was developed by the stoichiometric addition of Co(II) ions to a model composite (FePH) and termed as γ-CoFePH. The developed electrocatalyst shows a significant enhancement in ORR activity with improved E_onset and E_1/2 (3 mA cm^–2) values, where E_1/2 is −0.29 V as compared to −0.60 V for FePH, drifting toward Pt/C and exhibits a limiting current density of −6.3 mA cm^–2 which exceeds the commercially available Pt/C. The γ-CoFePH also displays superior resistance toward methanol poisoning and stability of over 40 000 s retaining 83.6% of the current density under alkaline medium.

Spatially dependent low-temperature to room-temperature degradation mechanisms for Li(Ni_0.5Mn_0.3Co_0.2)O₂/Li_xC₆ (NMC532/graphite) large format 50Ah Li-ion batteries were investigated. First, highly stressed regions of the cathode/anode are found to be exacerbated by extreme conditions (i.e., low-temperature cycling). The severe electrochemical polarization of large 50Ah electrodes at low temperature leads to substantial Li⁰ deposition and severe gassing at the regions of high stress (i.e., high curvature, edges, and electrode ripples). A series of analytical techniques (e.g., SEM, XPS, GC-MS, and Raman spectroscopy) found that Li⁰ plating (charge) or corrosion (storage) leads to severe gassing and decomposition products (including carbides). The expansion/contraction and extreme polarization during low-temperature cycling, was found to cause a ripple-type Li⁰ deposition on the electrode. Multilocation liquid nitrogen (N₂) Raman spectroscopy of electrodes indicates significant quantities of Li⁰ deposition reside at ripple peaks (high-stress region) and are found negligible at ripple troughs. Postmortem analysis discovered two failure scenarios that originate from low-temperature cycling, either nonthermal runaway venting or an internally shorted thermal runaway. It was found in the first case (storage) that LiC₆–Li⁰ undergoes severe corrosion and gassing during storage conditions (i.e., no movement, current, and temperature) and proceeds to trigger thermal runaway and ejection of materials (∼2 weeks). The second case (RT cycling after low temperature) resulted in nonthermal runaway overpressurized venting of the cell and release of detectable quantities of flammable/toxic gases (e.g., CO₂, CO, CH₄, and C₂H₂). The second event was found to be caused by competing reactions (i.e., Li⁰ stripping, Li⁰ corrosion, and severe gassing). This study finds that low-temperature Li⁰ plating and LiC₆–Li⁰ corrosion results in severe gassing, which exacerbates highly stressed regions (i.e., electrode buckling) and greatly compromises safety of the application— via nonthermal runaway venting when cycled (e.g., stripping of Li⁰ and gassing) and catastrophic thermal runaway when resting under storage (e.g., larger quantities of Li_xC₆–Li⁰ corrosion).

Interfacial architecture is key in tuning ferroelectric nanocomposites; however, the dynamic process of energy storage and release at the interface still remains a mystery. Herein, we experimentally demonstrated the direct proof of interfacial polarization, and interfacial energy distribution and coupling in ferroelectric nanocomposites by scanning probe microscopy (SPM) techniques. Remarkably, static reconstructions of the decay time (τ₂) reveals that the nanocomposite with carboxyl polystyrene nanoparticles (PS–COOH NPs) exhibits a much more obvious interfacial polarization layer than that of the nanocomposite with PS NPs, which is beneficial for achieving high energy density and high discharged efficiency. Besides, the spatial map of the decay time (τ₁) indicates that the size of polar nanoregions (PNRs) is scaled down by the cross-linking method, which is beneficial for achieving high energy density. Most importantly, SPM technology offers a means of visualizing the entire process of the energy release at the interface in real time and real space, which is advantageous to design hierarchical interface architecture for nanoscale energy utilization in capacitors, batteries, and fuel cells.

Nonaqueous aluminum-ion batteries are an interesting emerging energy storage technology, offering a plethora of advantages over existing grid energy storage solutions. Carbonaceous and graphitic materials are an appealing cathode material in this system, thanks to their low cost and excellent rate capabilities. The phenomenon of poor Coulombic efficiency in the first cycle, however, is a known issue among some types of carbons, the reasons for which are yet to be fully understood. In this work, we propose that such processes are caused by the formation of a solid–electrolyte interphase, in a similar fashion to graphite anodes in lithium-ion batteries. Using electrospun carbon nanofibers as a model material with tunable crystallinity, the cause of this phenomenon was found to be linked to the presence of surface defects in the cathode material and was further amplified by high surface area. The simple use of a binder polymer, however, helps mitigating the issue by shielding surface defects from direct contact with the electrolyte.

Driven by the increasing attention that the superionic conductors Li₃MX₆ (M = Y, Er, In, La; X = Cl, Br, I) have gained recently for the use of solid-state batteries, and the idea that a softer, more polarizable anion sublattice is beneficial for ionic transport, here we report Li₃ErI₆, the first experimentally obtained iodine-based compound within this material system of ionic conductors. Using a combination of synchrotron and neutron diffraction, we elucidate the structure, the lithium positions, and possible diffusion pathways of Li₃ErI₆. Temperature-dependent impedance spectroscopy shows low activation energies of 0.37 and 0.38 eV alongside promising ionic conductivities of 0.65 and 0.39 mS·cm^–1 directly after ball milling and the subsequently annealed Li₃ErI₆, respectively. Speed of sound measurements are used to determine the Debye frequency of the lattice as a descriptor of the lattice dynamics and overall lattice softness, and Li₃ErI₆ is compared to the known material Li₃ErCl₆. The softer, more polarizable framework from the iodide anion leads to improved ionic transport, showing that the idea of softer lattices holds up in this class of materials. This work provides Li₃ErI₆ as an interesting framework for optimization in the class of halide-based ionic conductors.

Two-dimensional transition metal oxyhydroxide (MOOH) nanostructures show great potential for application in catalysis, sensing, secondary batteries, and supercapacitors fields. Nonetheless, it is still a challenge to orient and hybridize MOOH nanosheets with carbon-free conductive materials (e.g., CuSe), and their uses in flexible in-plane asymmetric microsupercapacitors (AMSCs) are not explored. Herein, vertically oriented CuSe@FeOOH and CuSe@MnOOH hybrid nanosheet frameworks are alternately integrated on Au interdigital electrodes/polyethylene terephthalate substrate through a successive electrodeposition strategy without any template. Because of the unique geometric motifs and composition combination, those hybrid nanosheets frameworks exhibit greatly enhanced specific capacitance (543.9 F g^–1 for CuSe@FeOOH, 422.9 F g^–1 for CuSe@MnOOH). An in-plane AMSCs (CuSe@FeOOH//CuSe@MnOOH) is directly assembled by using poly(vinyl alcohol)-LiCl gel as the electrolyte. The as-fabricated AMSCs manifests large areal capacitance (20.47 mF cm^–2), remarkable cycle stability (95% remained after 32 000 cycles), excellent flexibility and mechanical stability. Moreover, it also exhibits a high volumetric energy density of 16.0 mW h cm^–3 and a power density of 1299.4 mW cm^–3, outperforming most recently reported in-plane microsupercapacitors. This work may promote the development of MOOH-based two-dimensional heteronanostructures and accelerate their applications in flexible energy storage or other clean energy fields.

The high cost and instability of platinum (Pt) counter electrodes (CEs) are two persistent issues in dye-sensitized solar cells (DSSCs). Here, ternary selenide NiCoSe and RuCoSe-nanostructured CEs are prepared by a simple one-step hydrothermal method. We mainly investigate the synergistic effect of ternary transition metals on the electrocatalytic properties. As a result, the photoelectric conversion efficiency (PCE) of NiCoSe CEs DSSCs with the enhanced efficiency up to 8.19% can be achieved. The excellent catalytic properties of the NiCoSe alloy selenide on I₃^– can be attributed to the expanded active sites, matched work function, redistributed electron structures, and reduced interface resistance. The facile preparation approach and outstanding catalytic behaviors offer applications of available DSSCs with low cost, superior stability, and promising performance.

Toward scalable manufacturing of perovskite solar panels, high-performance planar p–i–n perovskite solar cells (PVSCs) and modules have been demonstrated with blade coating and rapid thermal processing (RTP). The PVSCs made using RTP for less than 30 s have equivalent photovoltaic performance as devices fabricated from hot-plate annealing for 2 min. The resulting PVSCs show the best average power conversion efficiency (PCE) of over 18.47% from forward and reverse scans. Mini-modules with an active area of over 2.7 cm² exhibit a champion average PCE of over 17.73% without apparent hysteresis. To the best of our knowledge, these efficiencies are the highest for PVSCs processed by the combination of blade coating and RTP. Furthermore, both the blade coating and RTP were performed in an ambient environment, paving the way for the large-scale production of PVSCs through high-speed roll-to-roll printing.

Short cycle life of the lithium metal secondary battery (LMSB) is largely ascribed to the dendritic growth of lithium metal during the charging process followed by continuous electrolyte decomposition. To make up for this intrinsic drawback of lithium metal, two pioneering techniques, micropatterning on lithium metal and three dimensionally ordered microporous polyimide (3DOM PI) separator, are combined to ascertain their hybrid effect on the cycle performance of LMSB. When a unit cell consisting of LiNi_0.6Mn_0.2Co_0.2O₂/3DOM PI separator/patterned lithium metal is cycled at the charging and discharging c-rates of 0.3C and 1C (1C = 2.5 mA), respectively, above 80% of the initial discharge capacity is maintained even after 400 cycles, while a control cell with polyethylene separator survives only for 130 cycles. This tremendous improvement is ascribed to the combination effect of inducing preferential lithium electrodeposition reaction into the micropattern and the uniform distribution of lithium ions on the nonpatterned lithium surface region by the 3DOM PI separator. Thus, combining these two technologies is very promising for LMSB commercialization in the future.

Electrochemically polymerized anthraquinone derivatives on conductive carbon nanotubes are redox-active as organic cathode materials for lithium-ion batteries. Density functional theory calculations and electrochemical measurements reveal that the polymerized anthraquinone cathodes exhibit the multiple redox reactions with electrolyte ions through a bipolar charge storage mechanism: (1) the n-type doping/dedoping mechanism associated with Li⁺ binding in a potential window of 1.5–3.0 V versus Li and (2) the PF₆^–-involved p-type doping/dedoping mechanism in a potential window of 3.0–4.5 V versus Li. Polymerized 1-aminoanthraquinone (AAQ) shows progressive deactivation upon cycling because of the charge trapping effect. On the other hand, the polymerized 1,5-diaminoanthraquinone (DAAQ) delivers extraordinarily high charge capacities up to 311 mA h/g while effectively avoiding undesirable charge trapping behaviors. We establish the relationship between the structure and charge storage performance of the polymerized quinone derivatives, suggesting a high-performance organic cathode material for rechargeable battery applications.

Iridium (Ir)-based materials are known to be state-of-the-art electrocatalysts for catalyzing the oxygen evolution reaction (OER) in proton-exchange membrane (PEM) water electrolysis. However, it remains challenging for Ir-based catalysts to simultaneously achieve high catalytic activity and good stability in a strongly acidic environment. Herein, we report the fabrication of self-supported nanoporous ultrafine-grained IrO₂ electrodes (np-IrO₂) through the electrochemical activation of melt-spun Ir₁₂Al₈₈ ribbons under the OER conditions in 0.5 M H₂SO₄. The as-obtained np-IrO₂ needs only 240 mV to deliver 10 mA cm^–2 and can sustain continuous OER electrolysis in strong acid at an unusually high current density of 100 mA cm^–2 for 30 h without substantial degradation. Moreover, we find that the electrochemical activation of Ir₁₂Al₈₈ ribbons under the hydrogen evolution reaction (HER) conditions results in the formation of nanoporous IrAl alloy electrodes (np-IrAl), which show outstanding catalytic performance for HER in 0.5 M H₂SO₄. We further demonstrate that by using np-IrO₂ as an anode and np-IrAl as a cathode, we can accomplish overall acidic water splitting at 10 mA cm^–2 with a low voltage of 1.52 V. Remarkably, the np-IrO₂∥np-IrAl electrode pair is able to split water stably in 0.5 M H₂SO₄ at a high current density of 100 mA cm^–2 for up to 40 h, showing substantial promise for use in PEM water electrolysis.

Two strategies were investigated to improve the efficiency of organic solar cells (OSCs) with the aim of controlling the interfacial resistance in the devices: the use of a ternary active layer and the introduction of conjugated polymers. The ternary active layer was formed by introducing PC₇₁BM between a high-performance non-fullerene photoactive material P(Cl–Cl) (BDD = 0.2) and the IT-4F-based binary active layer, thereby reducing the interfacial resistance between the donor and acceptor via vertical phase separation. Furthermore, the introduction of the conjugated polymer PFN-Br created a well-dispersed separation attributable to enhancement of the interfacial contact with the active layer and simultaneous reduction of the interfacial resistance. Consequently, the synergetic effect of the ternary active layer and PFN-Br enhanced the short-circuit current density (J_SC) and fill factor (FF) to realize a power conversion efficiency (PCE) of 13.2%.

Conventional inorganic p-type conductive oxides, for example, NiO, CuO_X, and CuCrO_X, can serve as low-cost and efficient hole transport materials for wide-bandgap organolead halide perovskites [for example, MAPbI₃] but fail for low-bandgap Sn-rich organometallic perovskites, for example, (FASnI₃)_0.6(MAPbI₃)_0.4, where MA = (CH₃NH₃) and FA = (HC(NH₂)₂). In this work, we explore spinel Co₃O₄-based p-type conductive oxides as hole transport materials in organometallic halide MAPbI₃ and (FASnI₃)_0.6(MAPbI₃)_0.4 perovskite solar cells. We examine the structural, crystalline, optical, electrical, photo-electrochemical, and surface chemistry properties of spin-coated Co₃O₄ films without and with lithium doping. We find that lithium doping improves hole mobilities and film optical transparency and causes a lithium-enriched overlayer (e.g., LiCoO₂) forming at the Co₃O₄ film surface. As a result, lithium doping can maximize the hole transport properties of Co₃O₄ in our inverted planar perovskite solar cells, achieving about 14 and 7% light-to-electricity power conversion efficiencies (PCEs) for perovskite halides MAPbI₃ and (FASnI₃)_0.6(MAPbI₃)_0.4, respectively. This work underscores that cobaltite spinels hold promise for application as working HTLs for all kinds of organometallic halide perovskites.

Sodium-ion batteries (SIBs) are promising candidates for inexpensive and sustainable energy storage devices for the widespread utilization of intermittent renewable energy because of the natural abundance of sodium raw materials. However, since the ionic radius of Na⁺ is inherently larger than that of Li⁺, Na-based intercalation materials often suffer from poor stability and slow reaction kinetics. Regarding SIB cathodes, layered transition metals oxides (Na_xTMO₂) show promising theoretical capacities but low stability. In this work, a series of O3-NaFe_0.55Mn_0.45–xNb_xO₂ (x = 0, 0.01, 0.02, and 0.03) compounds are synthesized and show superior stability and rate-capability compared with the pure oxide. For instance, the best-performing sample, NaFe_0.55Mn_0.44Nb_0.01O₂, has a specific capacity of 127 mAh g^–1 and 80% capacity retention over 100 cycles at 0.1 C. Ex situ X-ray diffraction (XRD) result shows that the Nb incorporation could suppress TMO₂ slip and reduce the energy barrier of the O3–P3 phases’ transition. When coupled with a hard carbon (HC) anode in a full cell, the battery exhibits significant weight and volume energy and power densities. It is believed that Nb-doping enlarges lattice spacing of the oxide and partially reduces Mn⁴⁺ to Mn³⁺, increasing the ionic conductivity of the cathodic materials.

Glazing employing electrochromic materials can change their optical characteristics of transparency and absorption of solar radiation according to users’ needs by simultaneously reducing visible light and NIR transmission through the window. However, spectral selectivity has been becoming a key requirement in smart dynamic windows as it permits maximizing both visual and thermal comfort while minimizing energy consumption for heating, cooling, and lighting. Herein, a dual band electrochromic system is presented, which consists of an engineered nanocomposite electrode capable of advantageously combining the broad band plasmonic response of nanocrystalline indium-tin-oxide with high optical contrast of polyaniline. Their synergistical spectroelectrochemical features make possible the implementation of a four-state tunable electrochromic system (here referred to as “plasmochromic”), which permits selectively regulating optical transmittance in the visible and near-infrared range and exhibits excellent spectral selectivity (the ratio between visible light transmittance (T_LUM) and solar transmittance (T_SOL) can be tuned from 0.67 to 1.61) across a potentials window of only 1.2 V.

The crucial issue among lithium–oxygen batteries (LOBs) lies in the development of highly efficient catalysts to improve their large discharge–charge polarization, poor rate capability, and short cycle life. Herein, a composite of three-dimensional honeycomb graphene-supported a Mo/Mo₂C heterojunction has been synthesized and can be utilized as a self-supported LOB cathode directly. The LOBs based on the Mo/Mo₂C heterojunction composite cathode show a low overpotential of 0.52 V, a high discharge capacity of about 12016 mAh g^–1 at 100 mA g^–1, and a long-term cyclability (about 360 cycles) under a restricted capacity of 1000 mAh g^–1 at 100 mA g^–1, which exceeds the features of the majority of Mo-based catalysts for LOBs reported so far. Based on both experimental tests and density functional calculations, it is confirmed that the outstanding electrochemical performance is closely associated with a hierarchical porous structure for convenient oxygen/electrolyte diffusion, a large number of activity sites (interfaces/defects) for high capacity, and a high conductivity with metallic bonds for good rate capability. The method can be extended to prepare other metal-based heterojunctions.

Laser ignitable explosives are potential candidates in future applications for replacing toxic and very sensitive primary explosives, which are used in current devices. In this study, the literature unknown ligand 1-azidopropyl-5H-tetrazole (APT, 1) was synthesized for the first time and applied in energetic coordination compounds (ECC). The complexes are based on different 3d transition metals (Mn²⁺, Fe²⁺, Cu²⁺, and Zn²⁺) as well as various oxidizing anions (NO₃^–, ClO₄^–, and ClO₃^–) and were tested toward their capability as laser ignitable explosives. Furthermore, analogous complexes based on the literature known ligand 1-propyl-5H-tetrazole (PT, 2) were investigated for comparing the influence of the additional azide group toward the performance of the ECC. Toxicity measurements using Vibrio fischeri and the decreased sensitivities prove their usability as safer laser ignitable explosive with lower toxicities compared to currently used explosives.