Fig. 4: In situ HERFD-XAS and mechanistic investigation of formate selective CO2RR.

a Schematic representation of the in situ HERFD-XAS facility with an electrochemical gas diffusion flow cell. b In situ HERFD-XAS of Cu K-edge for CuXs and CuO. All potentials are reported vs RHE with 85% iR-correction. c Sketch of Cu 4p orbital alignment derived from the first derivative of in situ HERFD-XAS (left) and proposed scheme for the charge redistribution induced orbital interactions for corresponding CO2RR intermediates (right). Source data for (b) are provided in the Source Data file.