Morphological and Structural Characterization of (Pt, Au, and Ag) Nanoparticle/Zn-MOF-74 Composites

Metallic nanoparticles (NPs) were decorated onto Zn-MOF-74 crystals by photoreducing different metal precursors (Pt, Au, and Ag) using ultraviolet (UV) light in an aqueous solution with different metal concentrations without using additional stabilizers. X-ray diffraction revealed the three-dimensional structural integrity and crystallinity conservation of Zn-MOF-74 crystals during the UV decoration process. Raman spectroscopy showed a minor rearrangement in the structure of the Zn-MOF-74 crystal surface after NP decoration. X-ray photoelectron spectroscopy confirmed the metal oxidation states of Zn and NPs. High-resolution transmission electron microscopy images proved the surface decoration of Zn-MOF-74 crystals with spherical metallic NPs with diameters between 2.4 and 9.8 nm.


LIST OF FIGURES
The filtrated was washed with DI water and then with acetone for a few hours, filtered once more, and left to dry overnight, in the dark.5 mg AuNPs/Zn-MOF-74 nanocomposite (yield 50%) was obtained (Figure 2a).Synthesis UVII: NaOH(w) (0.1 M) was dropped in 700 µL of the HAuCl4 (0.1 M) solution (0.033 mmol) until pH=12.I-2959 (0.017 g, 0.076 mmol) was dissolved in 2.5 mL of DI water in the dark.40 mg of the Zn-MOF-74 powder and the metallic precursor solution were transferred to the UV reactor, and then the I-2959 solution was added.The final solution was stirred for 15 minutes under UV irradiationn, removed from the UV reactor, and filtered.The filtrated was washed with DI water and then with acetone for a few hours, filtered once more, and left to dry overnight, in the dark.27 mg AuNPs/Zn-MOF-74 nanocomposite (yield 68%) was obtained (Figure 2b).Synthesis UVI: AgNO3 (0.0056 g, 0,033 mmol) was solubilized in 10 mL of DI water, and I-2959 (0.008 g, 0.036 mmol) was dissolved in 10 mL of DI water in the dark.10 mg of the Zn-MOF-74 powder and the AgNO3 solution were transferred to the UV reactor, and then the I-2959 solution was added.The final solution was stirred for 15 minutes under UV irradiation, removed from the UV reactor, and filtered.The filtrated was washed with DI water and then with acetone for a few hours, filtered once more, and left to dry overnight, in the dark.5 mg AgNPs/Zn-MOF-74 nanocomposite (yield 50 %) was obtained (Figure 3a).Synthesis UVII: AgNO3 (0.012 g, 0.069 mmol) was solubilized in 700 µL of DI water, and I-2959 (0.017 g, 0.076 mmol) was dissolved in 2.5 mL of DI water in the dark.40 mg of the Zn-MOF-74 powder and the AgNO3 solution were transferred to the UV reactor, and then the I-2959 solution was added.The final solution was stirred for 15 minutes under UV irradiation, removed from the UV reactor, and filtered.The filtrated was washed with DI water and then with acetone for a few hours, filtered once more, and left to dry overnight, in the dark.28 mg AgNPs/Zn-MOF-74 nanocomposite (yield 70 %) was obtained (Figure 3b).

XPS
MeNPs/Zn-MOF-74 (Me = Pt, Au, Ag) powder samples were prepared over carbon stripe and excited with 1486,6 eV (Al Ka) X-ray beam radiation using the charge compensation functionally provided by the thermal Fisher ESCALAB QXi X-ray Photoelectron Spectrometer.Each observed survey spectrum is shown in Figure S7.

RAMAN
The assignments of the modes observed in Raman spectra of the MeNPs/Zn-MOF-74 (Me = Pt, Au, Ag) are summarized in Table S1 and in Table S2.

Figures
Figures S4 and S5 compare the powder X-ray diffraction pattern of Zn-MOF-74 and

Figure S4 :
Figure S4: Comparison of the experimental PXRD pattern of the composites: PtNPs/Zn-

Figure
FigureS7shows the size distribution of the NPs obtained from the analysis of the HRTEM

Figure S7 :
Figure S7: Size distribution of the particles in the (a) PtNPs/Zn-MOF-74 (UVI), (b) The high-resolution HRTEM images and the corresponding fast Fourier transform (FFT) patterns of Pt, Au and Ag nanoparticles representative of each sample are shown in Figures S9, S10 and S11.The selected area FFT pattern of the particle revealed the stacking of (111) and (200) planes.

Figure S8 :
Figure S8: HRTEM image and the FFT pattern of the selected Pt nanoparticle image.

Figure S9 :
Figure S9: HRTEM image and the FFT pattern of the selected Au nanoparticle image.

Figure S10 :
Figure S10: HRTEM image and the FFT pattern s of the selected Ag nanoparticle image.

Table S2 :
Assignment of vibrational bands from Raman spectra of Zn-MOF-74 and Zn-