Fig. 2: Operando time-resolved XAS characterization.

a Potential dependence of CO₂RR product selectivity on the CuO_x in 0.5 M CO₂-saturated KHCO₃ under the employment of redox shuttle. The error bars represented standard deviations based on three individual measurements. b Time-resolved variations using Redox Shuttle (R.S.) of Cu species in CuO_x and the corresponding electrochemical responses during CO₂RR at −0.75 V and c the corresponding time-resolved EXAFS spectra without phase-correction of CuO_x under CO₂RR. d Time-resolved variations using chronoamperometry (CA) of Cu species in CuO_x and the corresponding electrochemical responses during CO₂RR at −0.75 V and e the corresponding time-resolved EXAFS spectra without phase-correction of CuO_x under CO₂RR. The spectra were depicted in a 2D contour plot with interatomic distance (Å) on x-axis and with time (sec) on y-axis, while normalized Fourier transform magnitude served as corresponding intensity. Quantification of time-resolved chemical composition information extracted from operando Quick Cu XAS for CuO_x under eCO₂RR using redox shuttle (f) and conventional chronoamperometry (g). Each error bar indicated an estimated standard deviation based on the curve fitting of EXAFS spectra. Both cathodic potentials were −0.75 V and electrolyte was 0.5 M CO₂-saturated KHCO₃.