Si is among the highest theoretical capacity anodes for lithium-ion batteries, but it suffers from huge volume expansion during lithiation. Here we report a new approach to alleviating the volume change-induced degradation of Si anodes by mixing Si with a room-temperature liquid metal (LM), namely, Ga–Sn alloy. The Ga–Sn alloy is fluid with self-healing ability, acting as the liquid buffer for the Si upon lithiation and delithiation and healing the cracks caused by the volume expansion and contraction. The resulting Si/LM composite exhibits a high capacity and excellent cyclicability. The composite anode delivers a reversible capacity of ∼670 mAh/g after 1000 cycles, with an outstanding rate capability.

Graphitic carbon nitride (g-C₃N₄) is a promising photocatalyst for solar H₂ generation, but the practical application of g-C₃N₄ is still limited by the low separation efficiency of photogenerated charge carriers. Herein, we report the construction of ternary g-C₃N₄/graphene/MoS₂ two-dimensional nanojunction photocatalysts for enhanced visible light photocatalytic H₂ production from water. As demonstrated by photoluminescence and transient photocurrent studies, the intimate two-dimensional nanojuction can efficiently accelerate the charge transfer, resulting in the high photocatalytic activity. The g-C₃N₄/graphene/MoS₂ composite with 0.5% graphene and 1.2% MoS₂ achieves a high H₂ evolution rate of 317 μmol h^–1 g^–1, and the apparent quantum yield reaches 3.4% at 420 nm. More importantly, the ternary g-C₃N₄/graphene/MoS₂ two-dimensional nanojunction photocatalyst exhibits much higher photocatalytic activity than the optimized Pt-loaded g-C₃N₄ photocatalyst.

A new adsorbate-mediated strategy was developed to enhance the metal–support interaction of Cu/CeO₂, aiming to improve its catalytic activity and sintering resistance in the water–gas shift (WGS) reaction. By treating Cu/CeO₂ in a 20CO₂/2H₂ gas mixture for the formation of surface HCO_n (n = 2, 3), there was significant enhancement of the interaction between CeO₂ and Cu. The HCO_n adsorbate was removed through calcination in an O₂/Ar atmosphere at 400 °C for 6 h. The as-obtained Cu/CeO₂ catalyst was compared with the untreated counterpart in the WGS reaction. It was observed that CO conversion at 350 °C was 86% and 47%, respectively, over the two catalysts. The superiority of the former is attributed to the enhanced interaction between Cu and CeO₂. In a run of 15 h at 400 °C, the treated catalyst showed no obvious sign of deactivation.

Layered double hydroxide (LDH) and amorphous nickel–iron (oxy)hydroxides (Ni_1–xFe_xOOH) are emerging catalysts for the electrochemical oxygen evolution reaction (OER). It is still unresolved if the layered two-dimensional (2D) structure allows for active catalytic sites to exist below the traditional electrode/electrolyte interface. Herein, we utilized the surface interrogation mode of scanning electrochemical microscopy (SI-SECM) to directly measure active site densities in situ. We determined that Ni_0.8Fe_0.2OOH LDH showed a 10-fold increase in the active site density compared to rock salt Ni_0.8:Fe_0.2 oxide, giving direct evidence that water and hydroxide in the interlayer are able to create stable Ni^IV/Fe^IV active species at layers below the electrode/electrolyte interface. This result suggests that electrolyte permeability of the 2D LDH structure is a major contributor for its increased catalytic activity. Amorphous Ni_0.8:Fe_0.2 oxide also exhibits an anomalously high active site density and higher activity than Ni_0.8Fe_0.2OOH LDH.

An electrochemical thermocell realizes thermal to electric energy conversion when two electrodes operate the same reversible reaction but at different temperatures. Its Seebeck coefficient is determined by the entropy change of the redox reaction. Here we report a thermocell containing acetone and iso-propanol as the redox couple, which can achieve the highest reported Seebeck coefficient of −9.9 mV K^–1 when the hot side is above the boiling point of acetone. Vaporization entropy of acetone increases the total entropy change in the conversion of iso-propanol to acetone. In addition, a concentration gradient of acetone caused by evaporation and condensation increases the cell voltage significantly. Stable performance of the thermocell is enabled by a Pt–Sn catalyst operating in a neutral pH electrolyte solution. The possibility of utilizing a liquid–gas phase change to increase the Seebeck coefficient of thermocells opens a new venue for exploration.

Smart films with transmittance switching capabilities based on thermal stimuli are widely used in many optoelectronic applications. Despite the development of stably switchable materials, transition temperature control and broadband stepwise transmittance switching remain challenging topics. Additionally, reduction of the energy consumption during switching is also required. Here, we introduce an electrothermally driven film with switchable transmittance produced by stacking paraffin-immobilized polydimethylsiloxane gel on a transparent heater based on an aligned Cu/Ni network. The film shows stepwise transmittance switching capability with extremely low power consumption because of the controlled melting point of paraffin and the high-efficiency transparent heater.

A series of metal-free organic donor–acceptor (D–A) derivatives (ME01–ME06) of the known dye C281 were designed using first-principles calculations in order to evaluate their potential for applications in dye-sensitized solar cells (DSSCs). Their physical and electronic properties were calculated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). These include molecular properties that are required to assess the feasibility of a dye to function in DSSCs: UV–vis absorption spectra, light-harvesting efficiency (LHE), and driving forces of electron injection (ΔG_inj). ME01, ME02, and ME04 are predicted to exhibit broad absorption optical spectra that cover the entire visible range, rendering these three dyes promising DSSC prospects. Device-relevant calculations on these three short-listed dyes and the parent dye C281 were then performed, whereupon the dye molecules were adsorbed onto anatase TiO₂ surfaces to form the DSSC working electrode. Associated DSSC device characteristics of this dye···TiO₂ interfacial structure were determined. These include the light-harvesting efficiency, the number of injected electrons, the electron-injection lifetime, and the quantum-energy alignment of the adsorbed dye molecule to that of its device components. In turn, these calculated parameters enabled the derivation of the DSSC device performance parameters: short-circuit current density, J_SC, incident photon-to-electron conversion efficiency, IPCE, and open-circuit voltage, V_OC. Thus, we demonstrate a systematic ab initio approach to screen rationally designed D–A dyes with respect to their potential applicability in high-performance DSSC devices.

In this research contribution, the idea is created that Ln³⁺-doped nanosolid micelles have first been applied to enhance the photovoltaic properties of novel hybrid polymer solar cells (HPSCs). Among other publications in the literature, we have never found the same or similar work to be published previously. The new method of Ln³⁺-doped diblock copolymer (DBC) to develop nanosolid micelle luminescent materials is established. Very importantly the applicable technique to incorporate nanosolid micelles into PSCs by spin-coating on the surface of the indium tin oxide (ITO) layer is accomplished after comparing the different cooperation methods. This research contribution elucidates two novel HPSCs containing Ln³⁺ nanosolid micelles formed by Ln³⁺-doped diblock copolymer (Ln³⁺-DBC) and organic conjugated ligands. The Ln³⁺-DBC luminescent nanosolid micelles (LNSMs) are formed via coordination between Ln³⁺ ions and DBC, and are readily dispersed in a hydrophobic solvent. Nanosolid micelles can be incorporated into PSCs by spin-coating on the surface of the indium tin oxide (ITO) layer, to increase the absorption of sunlight. Critically, the presence of the LNSMs increases PSC absorption of light and increases the power conversion efficiency (PCE) of PTB7-Th/PC₇₁BM-based devices from 8.68% to 9.61%, increased by 10.71%, which is mainly caused by the enhanced short-circuit current density (J_sc), increased by 12.69% . In addition, the incorporation of LNSMs improved the stability of devices by protecting the active materials’ degradation from UV light.

Flexible thermoelectric generators (FTEGs) are emerging energy harvesting devices that have generated recent research interest because of their scalability and low cost. The fabrication of FTEGs requires printing of thermoelectric elements on flexible substrates. The low thermal conductivity, solution processability, and low cost of polymers make them an attractive choice for flexible devices. A major challenge in their adoption is their very low electrical conductivity. The electrical conductivity of conjugated polymers can be improved by doping and addition of active particles. This article describes enhancements in the thermoelectric properties of poly(3-hexylthiophene) (P3HT) polymer using 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) as a dopant. The highest electrical conductivity obtained was 1.6 S/cm for 17 wt % dopant in the polymer. The highest Seebeck coefficient (102 μV/K) and power factor (1.6 μW/mK²) were also obtained for the same dopant concentration. As a result of using optimized wt % of F4TCNQ dopant in P3HT polymer, we improved the power factor of P3HT by an order of magnitude compared to the highest power factor for P3HT reported in the literature. This doped polymer was subsequently evaluated as a potential binding system for p-type Sb₂Te₃ active particles. The results for the P3HT-Sb₂Te₃ composite are compared against epoxy-Sb₂Te₃.

Fireside corrosion is a serious concern in biomass firing power plants such that the efficiency of boilers is limited by high temperature corrosion. Application of protective coatings on superheater tubes is a possible solution to combat fireside corrosion. The current study investigates the corrosion performance of coated tubes compared to uncoated Esshete 1250 and TP347H tubes, which were exposed in two different biomass-fired boilers for one year. Data on the fuel used, temperature of the boilers, and temperature fluctuations are compared for the two boilers, and how these factors influence deposit formation, corrosion, and the stability of the coatings is discussed. The coatings (Ni and Ni₂Al₃) showed protective behavior in a wood-fired plant where the outlet steam temperature was 520 °C. However, at the plant that fired straw with an outlet steam temperature of 540 °C and where severe thermal cycling took place, both the Ni and Ni₂Al₃ coatings failed. This highlights the differences between the two biomass plants and demonstrates that a coating solution has to be tailored to the operation conditions of a specific boiler.

Recognition of unusual optoelectronic properties for two-dimensional (2D) layered organic–inorganic lead(II) halide materials (C_nH_2n+1NH₃)₂PbX₄ (X = I, Br, and Cl) has attracted intense renewed interest in this class of materials. Single crystals of the 2D layered materials (C₁₀H₂₁NH₃)₂PbBr₄ and pseudo-alloy (C₁₀H₂₁NH₃)₂PbI₂Br₂ were grown for photophysical evaluation. A 10-carbon alkylammonium cation was selected for investigation to provide strong dielectric screening in order to highlight quantum confinement effects of the anionic (PbX₄^2–) semiconductor layer. Single crystals of the 2D layered (C₁₀H₂₁NH₃)₂PbBr₄ compound display a characteristic free exciton with a binding energy of ca. 280 meV. Observation of a short photoluminescence lifetime of 2.8 ± 0.2 ns suggests that this electronic transition for the PbBr₄-based layered material has only singlet character. Sheets of (C₁₀H₂₁NH₃)₂PbBr₄ with thicknesses of a few layers were fabricated, and the dimensions were verified by AFM experiments. Excitonic emissions from (C₁₀H₂₁NH₃)₂PbBr₄ and (C₁₀H₂₁NH₃)₂PbI₄ exhibit relatively small spectral shifts from the bulk down to a thickness of five layers indicative of the strong confinement effect of the 10-carbon alkylammonium spacers. Single crystals of the pseudo-alloy (C₁₀H₂₁NH₃)₂PbBr₂I₂ give an excitonic absorption peak close to that of the tetrabromide (C₁₀H₂₁NH₃)₂PbBr₄ and an emission peak with a large Stokes shift to a position similar to that of the tetraiodide (C₁₀H₂₁NH₃)₂PbI₄.

Carbon dots (CDs) have been widely studied as sensitizers for metal oxide semiconductor electrodes. CDs/TiO₂ photoanodes were fabricated, and the regeneration kinetics of CDs were examined by scanning electrochemical microscopy in feedback mode. Regeneration rate constants of the CDs were obtained by using different concentrations of redox mediators and light intensities. Testing the regeneration rate of CDs within a single sensitized electrode provides some new insight into the analysis of the performance of CD-sensitized metal oxide semiconductor electrodes.

Zinc–air batteries, which typically employ aqueous electrolytes, have attracted much attention owing to their high energy density, low cost, and environmental friendliness. While the zinc–air battery is a promising solution for energy grid applications, freezing of the electrolyte is an important problem for operation in cold climates. The freezing point of the electrolyte can be affected not only by chemical composition but also by micro/nanoscale confinement in porous electrodes or separators, and this is the focus of our work. First, we find osmotic virial coefficients by fitting experimental freezing point data for various electrolytes that are used in zinc–air batteries. Second, we show how additives that improve the performance of the batteries may also lower the freezing point of the electrolyte system. Third, we show how the nanoscale confinement inside zinc–air batteries further decreases the freezing point; a 10 nm diameter capillary pore can suppress the local freezing point of the electrolyte by ∼10 °C. Finally, we map out the equilibrium mol% ice as a function of temperature, concentration, and confinement. This study provides insight that can be used to design specialized electrolytes for low temperature applications.

In order to solve the lack of energy sources, researchers devote themselves to the study of green renewable and economical supercapacitors. We demonstrate herein that the α-Ni(OH)₂ nanoplates/graphene composites are fabricated as active electrodes in supercapacitors with excellent cycling stability, high energy density, and power density. The advantages of graphene can complement the shortcomings of α-Ni(OH)₂ nanoplates to compose a novel composite. The α-Ni(OH)₂ nanoplates/graphene composite presents a high specific capacitance of 1954 F g^–1 at 5 A g^–1. The reason for the improving performance is attributed to graphene, which provides an improved conductivity and increased specific surface area by interweaving with α-Ni(OH)₂ nanoplates. It is particularly worth mentioning that the assembled asymmetric supercapacitor cells yield a high specific capacitance of 309 F g^–1 at 5 A g^–1 and light a 2 V LED sustainable for about 7 min, which may bring great prospects for further fundamental research and potential applications in energy storage devices.

Two new D–A donor polymers of PBDTNS-DTBO and PBDTNS-DTBT are designed and synthesized with a two-dimensional alkylthionaphthyl-substituted benzo[1,2-b:4,5-b′]dithiophene (BDTNS) unit. The influence of the BDTNS unit and another modified acceptor unit of benzo-oxadiazole (BO) (or benzo-thiadiazole (BT)) on optical, electrochemical, and photovoltaic properties is primarily studied. A stronger photoresponse with a higher external quantum efficiency is observed in the PBDTNS-DTBO film. As a result, PBDTNS-DTBO with a dialkoxy-substituted BO unit exhibits better photovoltaic properties than PBDTNS-DTBT with a difluorine-substituted BT unit in their solution-processing bulk heterojunction polymer solar cells (PSCs) using [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as an acceptor. The maximum power conversion efficiency of 8.02% with a short-circuit current density of 13.05 mA/cm² and a high fill factor of 71.5% is obtained in the PBDTNS-DTBO based devices. Our study indicates that PBDTNS-DTBO is a promising narrow-band photovoltaic polymer for the construction of high-performance PSCs.

While research efforts are devoted toward exploring low-cost electrocatalysts for hydrogen evolution reaction (HER), little attention is paid to another expensive component of the catalyst layer—ionomers. Both the electrocatalyst and a proportionately large amount of ionomer are required for a large-scale production of hydrogen. Presently, commercially available expensive Nafion is the state-of-the-art ionomer for proton conduction in the electrocatalyst layer. Interpolymer composites such as polymer acid-doped polyanilines (PANI) could be low-cost alternatives to Nafion. Highly water-dispersible PANI polymers doped with poly(2-acryl-amido-2-methyl-1-propanesulfonic acid) (PAAMPSA)—the polymer backbone of which is similar to that of Nafion—have been explored as cheaper alternatives to Nafion in acid medium. PANI-PAAMPSA, poly(ortho-toluidine)-PAAMPSA, and poly(meta-toluidine)-PAAMPSA have been used as ionomers in MoS₂ and CoSe₂ electrocatalysts. Electrocatalysts with PANI-PAAMPSA ionomers have achieved the highest HER activities and the lowest Tafel slopes in comparison to that with Nafion. Specifically, poly(meta-toluidine)-PAAMPSA has been found as a promising alternative to Nafion ionomer. Replacing expensive Nafion in the electrocatalyst layer with PANI-PAAMPSA-based ionomers would further reduce the cost of hydrogen in a large-scale production.

Electrochemical cation de/intercalation has long been investigated for energy-relevant applications, while anion de/intercalation is comparatively highly challenging, although promising for promoting the performance of materials. Herein, layered nickel hydroxychloride was selected as a model multianion-containing inorganic functional material to study. Hierarchical flower-like microspheres self-assembled from nanosheets were synthesized via a solvothermal method. The as-prepared nickel hydroxychloride was built up from neutral layers of [Ni(OH)_3/3Cl_3/3] octahedra, showing an expanded interlayer spacing of 0.57 nm. With this unique microstructure, Cl^– deintercalation and OH^– intercalation were accomplished through an effective nonelectrochemical process. The nickel hydroxychloride Ni(OH)_0.99Cl_1.01 with a maximum Cl^– ion content was found to possess the largest interlayer spacing, which when first employed as electrode materials for supercapacitor, delivered an ultrahigh specific capacitance of 3831 F/g at a current density of 1 A/g. For the latter case, Ni(OH)_2.18(H₃O)_0.18 with a maximum OH^– content showed a specific capacitance of 1489 F/g at 1 A/g. Expanded interlayer spacing associated with the anion de/intercalation is the key that enhances ion diffusion kinetics between layers. The methodology of anion de/intercalation reported in this work would provide hints of exploring novel multianion-containing materials with anion de/intercalation necessary for high-performance energy applications.

We study the spontaneous polarization of the archetypal semiconducting halide perovskite methylammonium lead triiodide (CH₃NH₃PbI₃) that is currently being investigated for use in thin film solar cells and light-emitting diodes. Using both lateral and vertical piezoresponse force microscopy (PFM) to image polycrystalline thin films, we observed domains in the piezoresponse that reversibly appear and disappear below and above the tetragonal-to-cubic phase transition temperature. Importantly, we observe these domains to exhibit a piezoresponse that is predominantly in-plane for films with the (110) plane oriented parallel to the substrate, providing a measure of the polarization associated with specific crystal planes. We characterize the polarization and its temporal response using both local switching spectroscopy and time-dependent PFM spectra. These data show hysteresis loops with the polarization switching with bias but relaxing back on time scales of several minutes. Our results suggest the existence of ferroelectric behavior due to off-center displacement of the Pb²⁺ cation, although the local polarization response is complicated by the presence of local ionic and electronic conductivity. Understanding the nature of these domains paves the way for further optimization of optoelectronic devices using CH₃NH₃PbI₃ perovskite material.

A facile and rapid surfactant-free microwave-assisted route is developed to synthesize 10 nm sized NiO nanoflakes with high pseudocapacitive performance for supercapacitor cells. The NiO nanoflakes exhibit mesoporous channels and a surface area as high as 206 m² g^–1 as revealed under BET study, while the structural identity verified by XRD and IR confirm the phase purity of NiO. NiO nanoflakes maintain ∼85% of their thermal stability at temperature 900 °C which can be related to strong intermolecular forces between the NiO nanoparticles held in the molecular matrix. Electrochemical performance investigated in 6 M KOH solution suggests maximum specific capacitance of 307 F g^–1 for the NiO∥NiO cell at 0.5 A g^–1 sustaining about 96% capacitance after being successfully cycled up to 3000 cycles. The NiO nanoflakes reveal high conductivity of 33.87 S cm^–1 at room temperature. Precisely, nanosized NiO bearing “flake” morphology is of particular interest due to the high surface to volume aspect and porosity features—the determining factors for swift ion diffusion into an electrode and improved redox reaction. The illustrated microwave-assisted route unfolds as a direct synthesis method to obtain nanosized NiO flakes with high surface area facilitating excellent device performance characteristics without involving any surface-capping agents.

Metal–air batteries and fuel cells show a great deal of promise in advancing low-cost, high-energy-density charge storage solutions for sustainable energy applications. To improve the activities and stabilities of electrocatalysts for the critical oxygen reduction and evolution reactions (ORR and OER, respectively), a greater understanding is needed of the catalyst/carbon interactions and carbon stability. Herein, we report how LaNiO₃ (LNO) supported on nitrogen-doped carbon nanotubes (N-CNT) made from a high-yield synthesis lowers the overpotential for both the OER and ORR markedly to enable a low bifunctional window of 0.81 V at only a 51 μg cm^–2 mass loading. Furthermore, the addition of LNO to the N-CNTs improves the galvanostatic stability for the OER by almost 2 orders of magnitude. The nanoscale geometries of the perovskites and the CNTs enhance the number of metal–support and charge transfer interactions and thus the activity. We use rotating ring disk electrodes (RRDEs) combined with Tafel slope analysis and ICP-OES to quantitatively separate current contributions from the OER, carbon oxidation, and even anodic iron leaching from carbon nanotubes.

SOFCs are a promising technology for high efficiency power generation with fuel flexibility; however, sulfur, a common contaminant in most hydrocarbon fuels, can cause severe anode degradation. Here we demonstrated that surface modification of Ni-GDC-based SOFC through nanoparticle infiltration drastically reduces the sulfur poisoning effect. Infiltrated SOFCs showed stable performance with sulfur-contaminated fuel for over 290 h, while unmodified SOFCs became inoperative after 60 h. We proposed that the nanosized GDC coating promotes sulfur removal through SO₂ formation by increasing the density of reaction sites and providing a ready supply of oxygen to those sites. The significant benefit provided by this electrode treatment is promising for the integration of SOFCs with established fuel compositions.

The architecture of a supercapacitor (SC) electrode plays a crucial role in defining the overall energy-storage performance of the SC. Layer-by-layer assembly of a reduced graphene oxide (rGO) and vanadium oxide (V₂O₅) (rGO/V₂O₅)-based heterostructure is patterned in interdigitated electrodes (IDEs) deposited directly on a flexible conducting current collector for the SC. The IDE pattern offers efficient accessibility to the electrolyte ions and a synergistic contribution for energy storage. An as-fabricated solid-state flexible sandwich-type SC with IDEs displays a more efficient energy-storage performance than a conventional solid-state flexible sandwich-type SC composed of rGO/V₂O₅ electrodes. Moreover, a solid-state flexible in-plane microsupercapacitor (MSC) is fabricated, which offers much higher capacitance (24 mF/cm² and 34.28 F/cm³) and energy density (3.3 μWh/cm² and 4.7 mWh/cm³). The as-fabricated flexible in-plane MSC displays a negligible capacitance loss of about 6.3% after 10 000 charge–discharge cycles and a superior stability of energy-storage performance towards mechanical deformation.

Inorganic p-type copper(I) thiocyanate (CuSCN) hole-transporting material (HTM) belongs to a promising class of compounds integral for the future commercialization of perovskite solar cells (PSCs). However, deposition of high-quality CuSCN films is a challenge for fabricating n-i-p planar PSCs. Here we demonstrate pinhole-free and ultrasmooth CuSCN films with high crystallinities and uniform coverage via delayed annealing treatment at 100 °C, which can effectively optimize the interfacial contact between the perovskite absorber and the electrode for efficient charge transport. A satisfactory efficiency of 13.31% is achieved from CuSCN-based n-i-p planar PSC. In addition, due to the superior transparency of p-type CuSCN HTMs, it is also possible to prepare bifacial semitransparent n-i-p planar PSCs, which eventually permits a maximum efficiency of 12.47% and 8.74% for the front and rear illumination, respectively. The low-temperature process developed in this work is also beneficial for those applications such as flexible and tandem solar cells on heat-sensitive substrates.

Epitaxial thin films of perovskite BaSn_1–xSb_xO_3−δ are fabricated by a simple chemical solution deposition method, and the relationship among the processing, the microstructure, and the optoelectronic property is systematically investigated. The process of multiple annealing combined with the postannealing under nitrogen ambient is the optimal procedure to fabricate high quality BaSnO_3−δ thin films. Sb doping in Sn sites facilitates the epitaxial growth of the BaSnO_3−δ grains. The Hall results show that with increasing Sb doping content the carrier density and the carrier mobility are enhanced and decreased, respectively, resulting in the highest room-temperature electrical conductivity of 260 S/cm in the BaSn_0.91Sb_0.09O_3−δ thin film. It is confirmed that the ionized Sb⁵⁺ and oxygen vacancies are the main scattering sources for carrier transport in BaSn_1–xSb_xO_3−δ thin films. The results will provide guidance for synthesis of BaSnO_3−δ-based and other donor-doped perovskite transparent conducting large-area thin films with low cost.

Herein, we designed a simple and energy-saving “ethanol-transfer-adsorption” method to prepare the activated carbon cloth/sulfur composite (ACC/S). Then, the prepared composite was wrapped in a thin-layered nickel-based hydroxide (NNH) to form a tree-bark-like structure. After irreversibly reacting with lithium to form a barrier layer with both good Li⁺ permeability and abundant functional polar/hydrophilic groups, this layer could retard the diffusion of lithium polysulfides by both physical confinement and chemisorption. As a result, the freestanding NNH/ACC/S cathode with 4.3 mg cm^–2 sulfur loading displayed a high-areal discharge capacity of 4.3 mA h cm^–2 over 100 cycles at 0.15 C. When cycled at 0.5 C, it still showed a discharge capacity of 650.0 mA h g^–1 over 350 cycles.

Most reported thermoelectric modules suffer from considerable power loss due to high electrical and thermal resistivity arising at the interface between thermoelectric legs and metallic contacts. Despite increasing complaints on this critical problem, it has been scarcely tackled. Here we report the metallization layer of Fe–Ni alloy seamlessly securing skutterudite materials and metallic electrodes, allowing for a minimal loss of energy transferred from the former. It is applied to an 8-couple thermoelectric module that consists of n-type (Mm,Sm)_yCo₄Sb₁₂ (ZT_max = 0.9) and p-type DD_yFe₃CoSb₁₂ (ZT_max = 0.7) skutterudite materials. It performs as a diffusion barrier suppressing chemical reactions to produce a secondary phase at the interface. Consequent high thermal stability of the module results in the lowest reported electrical contact resistivity of 2.2–2.5 μΩ cm² and one of the highest thermoelectric power density of 2.1 W cm^–2 for a temperature difference of 570 K. Employing a scanning transmission electron microscope equipped with an energy-dispersive X-ray spectroscope detector, we confirmed that it is negligible for atomic diffusion across the interface and resulting formation of a detrimental secondary phase to energy transfer and thermal stability of the thermoelectric module.

The exploration and rational design of cost-effective, highly active, and durable catalysts for oxygen electrochemical reaction is crucial to actualize the prospective technologies such as metal–air batteries and fuel cells. Herein manganese cobalt oxide nanoparticles anchored on carbon nanofibers and wrapped in a nitrogen-doped carbon shell (MCO/CNFs@NC) is successfully prepared. Benefiting from the synergistic effect between the core nanoparticles and nitrogen-doped carbon shell, MCO/CNFs@NC catalyst exhibits oxygen reduction reaction (ORR) activity with comparable onset potential (1.00 V vs RHE) and half-wave potential (0.76 V vs RHE) which is only about 40 mV lower than that of the state of art Pt/C catalyst. Furthermore, the MCO/CNFs@NC catalyst exceeds the Pt/C catalyst by a great margin in terms of stability in alkaline media. Additionally, MCO/CNFs@NC catalyst is strongly tolerant to methanol crossover, promising its applicability as cathode catalyst in alcohol fuel cells. Moreover, MCO/CNFs@NC catalyst exhibits the oxygen evolution reaction (OER) activity with low overpotential of 0.41 V at the current density of 10 mA cm^–2 and ORR/OER potential gap (ΔE) as low as 0.88 V, suggesting its strong bifunctionality. The Zn–air battery based on MCO/CNFs@NC catalyst is found to deliver a specific capacity of 695 mA h g^–1_Zn and an energy density of 778 W h kg^–1_Zn at a current density of 20 mA cm^–2. The mechanically rechargeable Zn–air battery based on MCO/CNFs@NC catalyst is also found to function continually by only reloading the consumed Zn anode and electrolyte. Furthermore, the electrically rechargeable battery based on MCO/CNFs@NC catalyst is found to function for more than 220 cycles with negligible loss of voltaic efficiency. Moreover, MCO/CNFs@NC is found to display a supercapacitive nature with a good discharge capacity of 478 F g^–1 at a discharge current density of 1 A g^–1.

H^– ion conductor materials have the great potential to enable high-energy density electrochemical storage based on hydrogen. Fast H^– conduction has been recently demonstrated in the La_2–x–ySr_x+yLiH_1–x+yO_3–y oxyhydride materials. However, little is known about the H^– diffusion mechanism in this new material and its unique structure. The origin of such exceptional H^– conduction in the oxide-based materials is of great interest. Using first-principles calculations, we studied the energetics and diffusion mechanisms of H^– ions as a function of structures and compositions in this oxyhydride system. Our study identified that fast H^– diffusion is mediated by H^– vacancies and that the fast two-dimensional or three-dimensional H^– diffusion is activated by different anion sublattices in different compositions. In addition, novel doping was predicted from ab initio computation to increase H^– conductivity in these materials. The unique two-anion-site feature in this structural framework enables highly tunable lattice and minimizes the blocking of anion diffusion by oxygen sublattice, allowing high mobile-carrier concentration and good diffusion network. This conclusion offers general guidance for future design and discovery of novel oxide-based anion conductors.

We report on the fabrication of CdSnP₂ thin films for photovoltaic applications. The phosphidation method, where a cosputtered Cd–Sn precursor thin film reacts with phosphorus gas, was utilized for the preparation of CdSnP₂ thin films. In order to establish the fabrication process, the temperature dependence on product phases was investigated, and CdSnP₂ thin films were obtained by the phosphidation at 350 °C for 30 min under the phosphorus vapor pressure of 10^–2 atm. CdSnP₂ thin films showed an n-type conduction. The resistivity, the carrier concentration and the mobility were evaluated to be 1.7–1.9 × 10² Ω cm, 2–7 × 10¹⁵ cm^–3, and 4.7–17 cm² V^–1 s^–1, respectively. CdSnP₂ thin films with relatively flat and smooth surfaces were obtained, although it was reported that ZnSnP₂ with the same crystal structure grew as the protrusion shape by the VLS growth mode. In order to investigate these difference in growth mechanism between CdSnP₂ and ZnSnP₂, the reaction process in the Cd–Sn–P system was investigated and discussed on the basis of the chemical potential diagrams. As the results, it was understood that Cd, Sn, and P₄ directly reacted to form CdSnP₂, while ZnSnP₂ was formed via the reaction among Zn₃P₂, Sn, and P₄ after Zn reacts with P₄ to produce Zn₃P₂. Therefore, it is speculated that this simple reaction route results in the high growth speed, and a smooth flat morphology was obtained in the fabrication of CdSnP₂ thin films.

Developing cheap and durable proton exchange membrane is crucial to promote the practical application of vanadium flow batteries (VFB). Here we report a simple and scalable method to fabricate a reinforced sulfonated poly(ether ether ketone) (SPEEK) membrane using a lithium-ion battery separator, ceramic-coated porous polyethylene (CCP), as a robust scaffold. With the confinement effect of the extremely stable CCP substrate, the reinforced SPEEK membrane (S@CCP) shows significantly improved chemical/mechanical stability and reduced vanadium ion permeability compared to the control SPEEK membrane. Accordingly, the S@CCP membrane demonstrates excellent rate performance and cycling stability than those of the benchmark Nafion 212 membrane. It exhibits stable performance over 1500 cycles at 160 mA cm^–2 with 99% of CE, 76% of EE and 0.126% of capacity decay per cycle. Meanwhile, the S@CCP membrane is highly resistant to temperature fluctuations over a wide range of −20–60 °C. The superior durability, wide temperature adaptability, and low cost suggest that the S@CCP membrane offers great promise as an ideal membrane for VFB application.

A vertically oriented rutile TiO₂ nanorod (NR) array, as an efficient electron transport layer (ETL), has been used in the perovskite solar cells (PSCs), and its microstructure has a great impact on the corresponding photovoltaic conversion efficiency (PCE). Here we employ a facile control strategy to modulate the microstructures of rutile TiO₂ NR arrays hydrothermally grown on the fluorine tin oxide (FTO) glass from a water–HCl solution of titanium n-butoxide (TBOT). It was found that introducing commercial TiO₂ nanoparticles (P25, Degussa) into the hydrothermal reaction system can efficiently slow down the growth rate of rutile TiO₂ NRs, thus causing the controllable preparation of an NR array on the FTO substrate. The device fabricated with an optimized NR array derived from the hydrothermal reaction solution containing P25 exhibits an improvement of 26.5% in PCE compared with the device fabricated with the NR array from the hydrothermal solution without P25, which is mainly attributed to the reduced charge recombination and the enhanced fill factor stemming from the better contact at the NRs array/perovskite interface. This successful finding demonstrates that the introduction of TiO₂ nanoparticles into the hydrothermal reaction solution of TBOT slows down the growth rate and the electron recombination process of the rutile TiO₂ NRs array, and thus acts as a facile control strategy for improving the photovoltaic performance of the rutile TiO₂ NRs array film-based PSCs.

Thin film energy storage technology has great potential in emerging applications. The concept of integrating a smart window and energy storage provides an ideally large area for a thin film battery and a structural power backup for an energy-efficient building. However, due to the limited number of candidate materials, there is still a significant challenge in optimizing the electrochemical energy storage and electrochromic properties. Here we demonstrate a novel nickel–carbonate–hydroxide (NCH) nanowire thin-film-based color-changing energy storage device that possesses a high optical contrast of ∼85% at 500 nm and a superior capacitance of more than 170 mF/cm² at 10 mV/s, as well as good cycling performance and controllability. Its versatility as a smart energy storage and display device is successfully demonstrated. In addition, the scalable and cost-efficient method for fabricating the NCH material and its compatibility with flexible substrates are also expected to expand its horizon for future applications.

Advanced composite membranes have been obtained by incorporation of the meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) into a sulfonated poly(etheretherketone) (sPEEK). The presence of porphyrins in their monomeric, dimeric, and aggregated forms into the membrane ionic domains have been investigated by static and time-resolved spectroscopic techniques. In particular, we succeeded in modulating the percentage of the different porphyrin species present into the proton-conducting channels acting on the dye load in the range 0.35–5 wt % porphyrin/polymer. The nanostructure of all the composite membranes has been investigated by small-angle X-ray scattering. This latter shows how the presence of TPPS porphyrins into the membrane ionic domains induces a reorganization of polymer chains in a more stable and organized lamellar-like structure with respect to the pristine polymeric matrix. Finally, the composite membranes have been used as proton exchange membrane for fuel cells (PEFCs) technology. The presence of porphyrins improved the performance of the membranes in terms of proton conductivity and stability. In particular, the 0.77 wt % composite membrane has been tested in a PEFC single cell simulating the operative conditions typical for portable applications, highlighting an improved stability compared to that of the sPEEK pristine membranes.

Lithium secondary batteries have attracted considerable attention due to their great potential to achieve ultrahigh energy density for future use. However, the Li metal anode suffers dendrite formation during repeated stripping/plating, hindering its practical realization. Herein, for the first time, an artificial solid electrolyte interphase layer, lithium phosphorus oxynitride (LiPON), is introduced for the lithium anode, and the viable application in high-energy lithium secondary pouch cell is probed. LiPON is stable with lithium and in the air, which can protect the lithium from the side reaction with H₂O and O₂ effectively. In low-energy batteries, the LiPON layer can enhance the efficiency of lithium deposition/dissolution and prolong the lifespan of the batteries. Further on, the discharge capacities of the lithium secondary cells with an energy density over 350 Wh kg^–1 deploying LiPON-coated Li anodes drop fast, and the batteries are prone to severe polarization leading to the termination of life. Nonuniform current density resulting from the cracks caused by the large mass of lithium stripping/plating is ascribed to being the decisive factor shortening the life of batteries. Generally speaking, more and further exploration should be focused on the modification of the large-area lithium anode to accomplish high-energy-density lithium batteries for practical applications.

Fluorine doped tin oxide (FTO) has been prepared via the direct chemical reaction of tin oxide powders and hydrofluoric acid at room temperature. The image of FTO displays a sphere-like structure with an average diameter of 40–100 nm. The spectra of X-ray photoelectron spectroscopy (XPS) demonstrate that fluorine is doped into SnO₂. A well-defined reduction peak at −0.50 V (vs SCE) is detected on the cyclic voltammogram (CV) of the nanosized FTO (n-FTO) electrode in CO₂-saturated 3.6 × 10^–4 μM H₂SO₄ solution of pH 5.5, which is strong evidence for the electrochemical reduction of CO₂. This result indicates that the n-FTO electrode in such an extremely low supporting electrolyte concentration exhibits good electrocatalytic ability toward CO₂ reduction under lower potentials. On the basis of reduction peak current as a function of scan rate, the reduction of CO₂ is first performed via adsorption of CO₂ on the n-FTO electrode surface, and then CO₂ is reduced. The product solution obtained under a constant potential of −0.90 V (vs Ag/AgCl with saturated KCl solution) is used for analysis of UV–vis spectra, ¹H NMR, and gas chromatography; the results demonstrate the presence of formic acid and methanol in the product solution, but formic acid is a main product. Faradaic efficiency for formic acid is 82.3%.

Discovering inexpensive and earth-abundant electrocatalysts to replace the scarce platinum group metal-based electrocatalysts holds the key for large-scale hydrogen fuel generation, which relies heavily on the theoretical understanding of the properties of candidate materials and their operating environment. The recent applications of the cobalt–dithiolene complex as promising electrocatalysts for the hydrogen evolution reaction have been broadened by forming low-dimensional metal–organic frameworks (MOFs) through polymerization. Using the Gibbs free energy of the adsorption of hydrogen atoms as a key descriptor, S atoms within one-dimensional MOFs are identified to be the preferred catalytic site for HERs. Our theoretical results further reveal that the activities of part S atoms can be improved by interacting with alkali metal cations from the electrolytes; specifically, the influence of cations on the performance is dependent on the electron affinity of cations. Our theoretical findings, therefore, demonstrate that the selection of electrolytes can be a promising approach to enhance the performance of electrocatalysts for HERs.

Microelectronic products are very sensitive to ionizing radiation (electrons, protons, heavy charged particles, X-ray, and γ radiation). Lead is the commonly used material for radiation protection. Bismuth deposition has become an interesting subject for the electrochemical community because of bismuth’s unique electrical, physical, and chemical properties. There is a limited number of authors dealing with deposition of continuous bismuth films onto metallic substrates by electrodeposition method. The conditions of Bi electrochemical deposition and the structure of Bi coatings were examined. X-ray diffraction patterns for all samples were indexed to rhombohedral Bi. Coatings with a signified texture (012) are formed in electrolyte without additives. With gelatin the growth texture changes, and the most intense reflex becomes (110). It was found that increasing gelatin concentration from 0.1 to 0.5 g/L leads to Bi microstructural refinement from 4–20 μm, to from 50 nm to 2 μm, respectively. The protection efficiency of Bi-based shields under 1.6–1.8 MeV electron radiation energy was measured. The electron beam attenuation efficiency was estimated by the changing of current–voltage characteristics of semiconductor test structures which were located behind the shields and without them. It has been determined that optimal protection effectiveness and mass-dimensional parameters are enabled by Bi shields with 2 g/cm² reduced thickness and 156 attenuation coefficient.

Free-standing nitrogen-doped cup-stacked carbon nanotube (NCSCNT) mats were synthesized and tested as anodes for potassium-ion batteries (KIBs). The edge-open structure character of the NCSCNTs allows a facile insertion of K⁺ ions into the carbon nanotubes. Combined with the nanosized feature and interconnected flexible structure, the NCSCNTs demonstrate impressive electrochemical performance with a reversible capacity of 323 mA h/g and a markedly improved rate capability retaining 75 mA h/g even at 1000 mA/g. Additionally, the free-standing NCSCNT mat electrodes eliminate the utilization of nonactive components of binders and conductive agents during the battery assembly and thereby significantly enhance the total specific capacity of the electrodes.

Li-ion capacitors, comprising a battery anode and a supercapacitor cathode, have been expected to bridge the gap between batteries and supercapacitors. However, the kinetics mismatch between the anodic sluggish insertion and the cathodic capacitive process has impeded the energy-storage potential of devices. Developing pseudocapacitive anode materials is urgently needed in that pseudocapacitance can deliver energy in the same time scale as electrostatic adsorption and offer a comparable level of energy storage to that of battery-type materials. Here we demonstrate an inside and outside synergistic nanoengineering strategy to synthesize nanoporous carbon-modified S-TiO₂ hybrid nanosheets, through which both the carbon layer and sulfur doping can be simultaneously generated in situ. Benefiting from the in situ S doping, the electronic and ionic conductivity of anatase TiO₂ nanoparticles is enhanced. The carbon-modified S-TiO₂ with dominant pseudocapacitance realizes an unprecedentedly high capacity of 550 mAh g^–1 at 0.3 C and excellent rate capability, outperforming that of the ever-reported TiO₂-based materials. Furthermore, a hybrid Li-ion capacitor based on the as-obtained carbon-modified S-TiO₂ electrode has been assembled, delivering a high energy density of 92.7 Wh kg^–1 and power density of 26 kW kg^–1 with a stable cycling life (85.8% after 10 000 cycles). Our work offers a new avenue for achieving electrode materials with extrinsic pseudocapacitance that is kinetically comparable to capacitive materials.

α-FeOOH (goethite) and γ-FeOOH (lepidocrocite) were found to be the main corrosion products of the steel cathode in the sodium chlorate process; the identification of the phases formed under reducing potentials, along with the study of the electrodes during the reoxidation, is fundamental to understanding their role in this process. In this work, FeOOH-based electrodes were investigated through in situ and in operando X-ray absorption spectroscopy (XAS), combined to electrochemical measurements (e.g., voltammetry and chronoamperometry). At sufficiently negative potentials (below −0.4 V vs RHE ca.) and under hydrogen evolution conditions an unknown iron(II)-containing phase is formed. A comprehensive analysis of the whole XAS spectrum allowed proposing a structure bearing a relation with that of green rust (space group P3̅1m). This phase occurs independently of the nature of the starting electrode (α- or γ-FeOOH). During electrochemical reoxidation, however, the original phase is restored, meaning that the reduced phase brings some memory of the structure of the starting material. Spontaneous reoxidation in air suppresses the memory effect, producing a mixture of α and γ phases.

3D printing has revolutionized a number of industries, but complete extension to electronics, robotics, and machines has yet to be realized. Current limitations are due to the absence of reliable and facile methods and materials for accessing conductive 3D printed materials. Traditional approaches to conducting nanocomposites (melt-mixing and solution-mixing) require high energy, are time-consuming, or demand functionalization for compatibilization between filler and matrix. Moreover, these methods usually require a high loading of nanofiller to establish a network of conductive particles (high percolation threshold). As such, access to conductive structures using standard 3D printing techniques and easily accessible starting materials is ideal for realizing next generation conductive polymer composites, with the added benefit of tailorability of size and shape of objects produced. Herein we present a facile method to prepare conductive polymer-based powder by assembling graphene oxide nanosheets on the surface of commercial polymer powder, then reduce the nanosheets to render them electrically conductive, and 3D print by selective laser sintering. Importantly, this simple and scalable method allows for polymer particles covered with carbon nanoparticles to be used to 3D print useful electrically conductive structures without a change to processing parameters compared to the polymer particles themselves. The chemical composition and mechanical and electrical properties of the composite materials were characterized, and we report the first example of a working electrostatic motor composed completely of 3D printed pieces, without any metal parts.

Nitrogen doping into a metal oxide is a conventional method to prepare a visible-light-responsive photocatalyst. However, the charge imbalance that results from aliovalent anion substitution (i.e., O^2–/N^3– exchange) generally limits the concentration of nitrogen that can be introduced into a metal oxide, which leads to insufficient visible-light absorption capability. Here we report an effective route to synthesize nitrogen-doped metal oxide using KTiNbO₅, which is a compositionally flexible layered oxide and can be exfoliated into nanoscale sheets. KTiNbO₅ has a unique layered structure, in which Ti⁴⁺ and Nb⁵⁺ coexist in the same two-dimensional sheet, and controllable Ti⁴⁺/Nb⁵⁺ ratios while maintaining the original KTiNbO₅-type structure. The use of a Nb-rich oxide precursor could allow for the improvement in the introduction of nitrogen compared with stoichiometric KTiNbO₅ during thermal ammonolysis with ammonia gas. Reassembled KTiNbO₅ nanosheets with a larger surface area were found to be more useful as a precursor than the layered precursor in terms of nitrogen introduction and thus yielded more pronounced visible-light absorption and photocatalytic activity for water oxidation.

PEDOT-coated WO_x nanorodes (NRs) were prepared for the first time by simply stirring WO_x nanowires (NWs) with 3,4-ethylenedioxythiophene (EDOT) in aqueous solution. A series of spectroscopic characterizations indicate that the polymerization of EDOT occurrs not only on the surface but also along the [010] planes of WO_x NW, resulting in the truncation of long WO_x NW to produce WO_x@PEDOT NRs with abundant oxygen vacancies. Furthermore, WO_x@PEDOT NRs were used to prepare a hole transport layer (HTL) in planar p–i–n perovskite solar cells (PeSCs). The WO_x@PEDOT-based devices yielded a comparable average power conversion efficiency (PCE) of 12.89% with improved open-circuit voltage (V_OC) and fill factor (FF) but lower short-circuit current density (J_SC), as compared to the devices with conventional PEDOT:PSS (12.88%). The observed device performance is mainly attributed to the better perovskite texture on the WO_x@PEDOT HTL, improved energy alignment, and suppressed charge recombination at the WO_x@PEDOT/perovskite interface as well as lower charge conductivity of the WO_x@PEDOT HTL. In addition, the PeSCs based on WO_x@PEDOT-doped PEDOT:PSS showed remarkably improved PCEs up to 14.73%, which may be ascrible to the combined merit of WO_x@PEDOT NRs and PEDOT:PSS. More impressively, benefiting from the inherent neutral nature of WO_x@PEDOT NRs, WO_x@PEDOT-based devices exhibited obviously improved stability compared to that with PEDOT:PSS HTL. These results thus demonstrate a path toward the development of new hybrid nanostructures for efficient and stable PeSCs.

Cost-efficient thin-film devices that emit in the near-infrared (NIR) range promise a wide range of important applications. Here, the synthesis and NIR application of a series of copolymers comprising poly[indacenodithieno[3,2-b]thiophene-2,8-diyl] (PIDTT) as the host and different donor–acceptor–donor (DAD) segments as the guest are reported. We find that a key design criterion for efficient solid-state host-to-guest energy transfer is that the DAD conformation is compatible with the conformation of the host. Such host–guest copolymers are evaluated as the emitter in light-emitting electrochemical cells (LECs) and organic light-emitting diodes, and the best performance is invariably attained from the LEC devices because of the observed balanced electrochemical doping that alleviates issues with a noncentered emission zone. An LEC device comprising a host–guest copolymer with 4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene as the donor and benzo[c][1,2,5]thiadiazole as the acceptor delivers an impressive near-infrared (NIR) performance in the form of a high radiance of 1458 μW/cm² at a peak wavelength of 725 nm when driven by a current density of 500 mA/cm², a second-fast turn-on, and a good stress stability as manifested in a constant radiance output during 3 days of uninterrupted operation. The high-molecular-weight copolymer features excellent processability, and the potential for low-cost and scalable NIR applications is verified through a spray-coating fabrication of a >40 cm² large-area device, which emits intense and uniform NIR light at a low drive voltage of 4.5 V.

Sputter-deposited Al/CuO multilayers exhibit fast combustion reactions in which an exothermic chemical reaction wave—controlled by the migration of oxygen atoms from the oxide matrix toward the aluminum layers through interfacial layers—moves throughout the multilayer at subsonic rates (meters per second to tens of meters per second). We directly observed the structural and chemical evolution of Al/CuO/Al multilayers upon heating to 700 °C using high-magnification transmission electron microscopy (TEM) and scanning TEM, providing simultaneous sub-nanometrer imaging resolution and detailed chemical analysis. Interestingly, as deposited, the trilayer is characterized by two distinct interfacial layers: 4.1 ± 0.2 nm thick amorphous alumina and a 15 ± 5 nm thick mixture of AlO_x and Cu_xAl_yO_z, at the bottom interface and top interface, respectively. Upon heating, we accurately characterized the evolving nature and structure of these interfaces, which are rapidly replaced by the reaction terminal oxide (Al₂O₃). For the first time, we unraveled the release of gaseous O from the sparse columnar and defective CuO well below reaction onset (at ∼200 °C) which accumulates at interfaces and contributes to initiate the Al oxidation process at the vicinity of native interfaces. The oxidation process is demonstrated to be accompanied by a continuous densification and modification of the CuO layer. Between 300 and 350 °C, we observed a brutal shrinkage of the CuO layer (14% loss of its initial thickness) leading to the mechanical fracture in the top alumina growing layer. Consequently, this latter becomes highly permeable to oxygens leading to a brutal enhancement of the oxidation rate (×4). We also characterized stressed-induced interfacial delamination at 500 °C pointing clearly to the mechanical fragility of the top interface after the CuO transformation. Altogether, these results permit one to establish a multistep reaction scenario in Al/CuO sputter-deposited films supporting to an unprecedented level a mechanistic assignation of differential scanning calorimetry peaks. This study offers potential benefits for the development of aging models enabling the virtual prediction of the calorimetric response of exothermic Al/CuO thin-film reactions.

Persistent bubble accumulation during the oxygen evolution reaction (OER) can effectively block catalytically active surface sites and reduce overall system performance. The OER is an essential half-reaction with relevance to metal–air batteries, fuel cells, and water electrolysis for power to gas applications. The renewable energy sector could benefit from the identification of surface morphologies that can effectively reduce the accumulation of bubbles on electrocatalytic surfaces. In this work, regular dimpled nickel (Ni) features were prepared to investigate how electrode morphology and therefore its roughness and wetting properties may affect the efficiency of the OER. The dimpled Ni features were prepared using spherical poly(styrene) (PS) templates with a diameter of 1 μm. The electrodeposition against regular, self-assembled arrays of PS templates was tuned to produce four types of dimpled features each with a different depth. Enhancements to the OER efficiency were observed for some types of dimpled Ni features when compared to a planar electrodeposited Ni electrode, while the dimpled features that were the most recessed demonstrated reduced efficiencies for the OER. The findings from this study emphasize the influences of electrode surface morphology on processes involving electrocatalytic gas evolution.