Defect-rich copper phyllosilicate promotes electrochemical CO₂ reduction to C₂₊ alcohols

A central goal in designing catalysts for electrochemical CO₂ reduction (CO₂RR) is to achieve high selectivity towards multicarbon (C₂₊) products that can be used in fuel and fine chemical production. Copper has long been prioritized in CO₂RR electrocatalyst development due to the ability of Cu⁺ species to enhance C₂₊ product formation. This work reports the synthesis of defect-rich copper phyllosilicate (CuPS, Cu₂Si₂O₅(OH)₃) that contains high Cu⁺ content, but no crystalline Cu₂O, using a laser synthesis in liquid approach. This catalyst achieves good CO₂RR selectivity toward ethanol and n-propanol, with faradaic efficiencies of 7.6% and 8.1%, respectively. Computational modeling shows that introducing oxygen vacancies through the removal of surface hydroxyl groups on the Cu₂Si₂O₅(OH)₃ chrysocolla phase promotes C-C coupling and suppresses formation of undesired C₁ products. These findings suggest that imparting defects such as oxygen vacancies into CuPS can be a promising strategy to enhance selectivity toward C₂₊ alcohols in the CO₂RR.