Formation of Enriched Vacancies for Enhanced CO2 Electrocatalytic Reduction over AuCu Alloys

Electroreduction (ER) of carbon dioxide (CO2) is a promising way to curb excessive CO2 emission and produce value-added products. Gold–copper (AuCu) alloys are known to exhibit eminent CO production performance toward CO2ER. However, it still remains a grand challenge to balance *COOH and *CO bonding and to further decrease CO onset potential. This Letter describes the construction of Cu vacancies at an abrupt surface over a dealloyed AuCu catalyst to effectively decrease the overpotential and increase CO faradaic efficiency. Dealloyed Au3Cu exhibited a 90.2% CO faradaic efficiency at ？0.38 V vs RHE and a 418.60 A/g CO mass current density at ？0.8 V. vs RHE, achieving the record for CO production among AuCu catalysts. Combining the experimental and theoretical results, we concluded that the improved performance primarily results from the enhanced *COOH absorption