Grain boundary generation via steering CuxP2Ox+5 precursor composition enhances CO electrolysis

Abstract

The selective electrochemical conversion of CO₂/CO into valuable C₂₊ oxygenates and hydrocarbons using Cu-based catalysts is regarded as a promising strategy for carbon cycle utilization. Herein, we synthesized Cu_xP₂O_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_xP₂O_x+5 cell volume. Reconstructed Cu_xP₂O_x+5 shows a grain boundary-dependent performance in CO electrolysis, with a C₂₊ faradaic efficiency over 90% at a current density greater than 1.0 A cm⁻². Among them, reconstructed Cu₅P₂O₁₀, with the highest surface density of grain boundary, achieves a C₂₊ current density of 1.70 A cm⁻² and a C₂₊ 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 H₂O dissociation sites, which facilitate *CO–COH formation for C₂₊ production.