Fig. 4: Catalyst evolution during CO2RR characterized by operando XAS.
a XANES at the Cu K-edge of the CuO NS catalysts at OCP in 0.1 M KHCO3 at pH 6.8 during 130 min CO2RR at −0.84 VRHE. b Linear combinations (with the weighting factors as fit parameters) of Cu foil and the CuO NS catalysts at OCP were fitted to experimental data of the CuO NS catalysts during 130 min CO2RR at −0.84 VRHE. Colored lines represent the experimental data and black lines the linear combinations. c Amount of Cu metal in the CuO NS catalysts during 130 min CO2RR at −0.84 VRHE. Values are obtained by linear combinations (with the weighting factors as fit parameters) of Cu foil and the CuO NS catalysts at OCP, which were fitted to experimental data. d FT of k3-weighted EXAFS at the Cu K-edge of the CuO NS film at OCP and during 130 min CO2RR at −0.84 VRHE in 0.1 M KHCO3 at pH 6.8. Colored lines represent the experimental data and black lines the simulations. The distance on the x-axis is reduced by 0.35 Å relative to the real internuclear distance. e EXAFS (k3 weighted) at the Cu K-edge of the CuO NS catalysts at OCP and during 130 min CO2RR at −0.84 VRHE in 0.1 M KHCO3 at pH 6.8. Colored lines represent the experimental data and black lines the simulations. Coordination numbers of the first Cu-O f coordination sphere and the first intermetallic Cu-Cu g shell (Details of the fit error and Fourier-filtered error can be found in the Supplementary Information). Catalyst loading: 100 μg cm−2.
