Fig. 1: Schematic representation of the operando Raman analysis used in this study and the physicochemical characteristics of Cu(Tpy)2 and Cu(Tpy)2-KB.

a A scheme illustrating the operando Raman study on the CO2RR process of Cu(Tpy)2-KB@GC electrocatalyst. b Raman spectroscopy, c UV-vis and (d) XPS Cu2p spectra of Cu(Tpy)2 and Cu(Tpy)2-KB. H atom in white, C atom in gray, N atom in blue, O atom in red and Cu atom in brown, respectively.