This study presents a strategy to enable efficient CO₂/COR electrolysis by in situ copper faceting, which preferentially exposes Cu(100) facets. The Cu(100) facets are more active for C-C coupling, leading to higher Faradaic efficiencies and current densities for multicarbon (C₂⁺) products. The researchers introduced a phosphate ligand that facilitates the co-adsorption of CO and hydroxide ions, steering the surface reconstruction to Cu(100). The resulting Cu catalyst achieved current densities of >500 mA cm⁻² and Faradaic efficiencies of >83% for C₂⁺ products from both CO₂ reduction and CO reduction. The catalyst maintained a 37% full-cell energy efficiency and a 95% single-pass carbon efficiency over 150 hours of operation. The study also demonstrated that the Cu(100)-rich catalyst is stable and efficient for both CO₂ and CO electrolysis, with high carbon efficiency and energy efficiency. The results show that the in situ copper faceting strategy significantly improves the performance of CO₂/COR electrolysis, making it a promising approach for carbon recycling and renewable energy applications.This study presents a strategy to enable efficient CO₂/COR electrolysis by in situ copper faceting, which preferentially exposes Cu(100) facets. The Cu(100) facets are more active for C-C coupling, leading to higher Faradaic efficiencies and current densities for multicarbon (C₂⁺) products. The researchers introduced a phosphate ligand that facilitates the co-adsorption of CO and hydroxide ions, steering the surface reconstruction to Cu(100). The resulting Cu catalyst achieved current densities of >500 mA cm⁻² and Faradaic efficiencies of >83% for C₂⁺ products from both CO₂ reduction and CO reduction. The catalyst maintained a 37% full-cell energy efficiency and a 95% single-pass carbon efficiency over 150 hours of operation. The study also demonstrated that the Cu(100)-rich catalyst is stable and efficient for both CO₂ and CO electrolysis, with high carbon efficiency and energy efficiency. The results show that the in situ copper faceting strategy significantly improves the performance of CO₂/COR electrolysis, making it a promising approach for carbon recycling and renewable energy applications.