Stabilizing copper oxidation states via lattice oxygen overflow on Sb2O4 for durable CO2 electroreduction to CO

An optimal oxygen spillover–SMSI window is theoretically identified to suppress catalyst deactivation. • Persistent Cu δ⁺ /Sb–O interfacial sites contribute to enhanced catalyst stability during CO 2 electroreduction. • Long-term electrolysis confirms that CuO x /Sb 2 O 4 maintains high FE CO for over 600 h at −0.9 V vs. RHE. Cu-based catalysts have shown great potential for CO 2 electroreduction, while facing a critical stability challenge. One fundamental cause lies in the fact that the active Cu δ ⁺ species are inherently prone to be reduced under operating conditions, leading to rapid structure reconstruction and activity degradation. Herein, a coupling strategy involving the deposition of CuO x on oxygen-donating metal oxide (CuO x /MO) was proposed to stabilize Cu δ+ via dynamic oxygen migration, thereby enhancing catalytic durability. A theoretical screening framework was developed, using oxygen vacancy formation energy ( E OV ) and CuO x desorption energy ( E CuOV ) as the descriptors to assess oxygen spillover propensity and metal-support interaction, respectively. This led to the selection of 9 promising candidates for stability enhancement, which were validated experimentally. Notably, Sb 2 O 4 stands out as the optimal support, endowing CuO x exceptional long-term stability, maintaining a CO Faradaic efficiency of 91.2% at –0.9 V vs. RHE for over 600 h of continuous operation. Comprehensive characterizations further revealed that sustained lattice-oxygen-mediated interfacial oxygen exchange, together with strong metal-support interactions, is proposed to contribute to the robust Cu δ+ /Sb-O interface, promoting CO desorption and suppresing reconstruction. This work elucidates the dynamic evolution of CuO x /MO interfaces under CO 2 RR conditions and establishes a generalizable design paradigm for stabilizing reactive oxidation states via engineered oxygen spillover. Download: Download high-res image (184KB) Download: Download full-size image A lattice-oxygen-overflow strategy is proposed to stabilize Cu δ⁺ sites for durable CO 2 electroreduction to CO. DFT screening identifies Sb 2 O 4 as an optimal oxygen-donating support with suitable oxygen vacancy formation energy and strong CuO x –support interaction. Dynamic oxygen migration from Sb 2 O 4 preserves the Cu δ⁺ /Sb–O interface, suppresses Cu reconstruction, and promotes CO desorption. As a result, CuO x /Sb 2 O 4 achieves 91.2% CO Faradaic efficiency at –0.9 V vs. RHE and maintains stable operation for over 600 h.demonstrating a general design principle for stabilizing reactive oxidation states through engineered lattice oxygen spillover.