Fig. 3: Operando Cu K-edge and Zn K-edge EXAFS spectra. | Nature Communications

Fig. 3: Operando Cu K-edge and Zn K-edge EXAFS spectra.

From: Operando high-pressure investigation of size-controlled CuZn catalysts for the methanol synthesis reaction

Fig. 3

The FT magnitude of the a Cu K-edge and b Zn K-edge EXAFS spectra for Cu/ZnO/Al2O3, CuZn/SiO2, and CuZn/Al2O3 catalysts in their initial state (dashed lines), and under operando conditions in CO2+CO+H2, p = 20 bar, T = 220°C (solid lines). The magnitude of the FT of the EXAFS spectra for CuZn/SiO2 during c a reduction in 10% H2/He for 20 h at 245°C and d at temperatures between 245 and 600°C. The reference spectra for a Zn foil, ZnO, CuO, and Cu foil are also shown. The highlighted areas in b–d indicate the region where the Zn–M bond develops under reaction conditions. The latter is also shown in the inset in b, with spectra α, β, γ, δ, and ε corresponding to consequent measurements at 220°C/20 bar, 280°C/20 bar, 280°C/40 bar, and 320°C/40 bar. To enhance the display of the referred features, different k-ranges were used for the Fourier transform in a, b 1–10.5 Å−1, c 3–12 Å−1, and d 1–10 Å−1. The observed changes are schematically presented in e for CuZn/Al2O3 and f for CuZn/SiO2.

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