Metal-Organic Framework-Derived Partially Oxidized Cu Electrocatalysts for Efficient CO₂ Reduction Reaction Toward C₂₊ Products

Cu-based metal-organic frameworks (Cu-MOFs) electrocatalysts are promising for CO₂ reduction reactions (CO₂RR) to produce valuable C₂₊ products. However, designing suitable active sites in Cu-MOFs remains challenging due to their inherent structural instability during CO₂RR. Here we propose a synergistic strategy through thermal annealing and electrochemical-activation process for in-situ reconstruction of the pre-designed Cu-MOFs to produce abundant partially oxidized Cu (Cu^δ+) active species. The optimized MOF-derived Cu^δ+ electrocatalyst demonstrates a highly selective production of C₂₊ products, with the Faradaic Efficiency (FE) of 78 ± 2% and a partial current density of −46 mA cm⁻² at −1.06 V_RHE in a standard H-type cell. Our findings reveal that the optimized Cu^δ+-rich surface remains stable during electrolysis and enhances surface charge transfer, leading to an increase in the concentration of *CO intermediates, thereby highly selectively producing C₂₊ compounds. This study advances the controllable formation of MOF-derived Cu^δ+-rich surfaces and strengthens the understanding of their catalytic role in CO₂RR for C₂₊ products.