Bifunctional Catalysis Drives Efficient and Ethanol-Producing Aqueous Zn-CO2 Batteries.

Bifunctional electrocatalysts that simultaneously drive CO2 reduction (CO2RR) and oxygen evolution (OER) in neutral electrolytes are essential for aqueous Zn-CO2 batteries (AZCBs), but conventional designs prioritize CO2RR and are often incompatible with OER, resulting in low energy efficiency, poor reversibility, and rapid degradation of batteries. Here, we introduce a unified catalyst architecture integrating Cu and Ni single atoms with boron-, nitrogen-co-doped carbon (CuNi@BNC-T). Heteroatom co-doping stabilizes high single-atom loadings, enhances metal-support interactions, and suppresses carbon corrosion, while N-coordinated Cu+ and Ni3+ sites cooperatively boost CO2RR-OER, enabling ethanol formation and low-overpotential OER. This strategy achieves a 0.7 V voltage gap at 5 mA cm-2, 522 h cycling at 20 mA cm-2, and first ethanol production via AZCBs with energy efficiency of 88% (flow-cell). By elucidating previously unresolved degradation pathways, this work also correlates catalyst dynamics with battery failure, establishing design principles for durable bifunctional catalysts in aqueous Zn-CO2 systems.