Grain boundary generation steering CuPO precursor composition enhances CO electrolysis

The selective electrochemical conversion of CO 2 /CO into valuable C 2+ oxygenates and hydrocarbons using Cu-based catalysts is regarded as a promising strategy for carbon cycle utilization. Herein, we synthesized Cu x P 2 O x +5 ( x = 2, 4, and 5) by introducing phosphorous in cupric oxide, which is electrochemically reconstructed into metallic Cu in situ with a highly porous structure during CO electrolysis. Physicochemical characterizations demonstrate various degrees of grain boundary generation, which depends on the Cu atom density in the Cu x P 2 O x +5 cell volume. Reconstructed Cu x P 2 O x +5 shows a grain boundary-dependent performance in CO electrolysis, with a C 2+ faradaic efficiency over 90% at a current density greater than 1.0 A cm −2 . Among them, reconstructed Cu 5 P 2 O 10 , with the highest surface density of grain boundary, achieves a C 2+ current density of 1.70 A cm −2 and a C 2+ formation rate of 575.8 μmol min −1 . Operando Raman spectra reveal strong CO adsorption with dominant configurations of atop and bridge. Density functional theory calculations indicate that grain boundary provides active C-C coupling and H 2 O dissociation sites, which facilitate *CO-COH formation for C 2+ production. High-density grain boundary generation via electrochemical reconstruction is achieved by adjusting Cu atom density in the precursor lattice of Cu x P 2 O x +5 , thus promoting CO electrolysis for C 2+ production.