Coralloid Au enables high-performance Zn–CO2 battery and self-driven CO production

Abstract

High current density and low energy consumption in electrocatalytic CO₂ conversion are two key factors for practical CO₂ fixation. Herein, coralloid Au was prepared via a facile electrodeposition approach, which showed remarkable performance in a membrane electrode assembly system with the highest CO faradaic efficiency (FE_CO) of 94.2% at −60 mA cm⁻² and 45.3 ml h⁻¹ CO productivity. By using coralloid Au, we built an aqueous Zn–CO₂ battery; it yields a high power density of 0.7 mW cm⁻², 68 h cyclability, and maintains 63% FE_CO at a discharge current density of −3.0 mA cm⁻². Further, a self-driven CO₂ electrolysis unit powered by the as-assembled Zn–CO₂ battery was developed for the first time, which achieves a maximum CO productivity of 0.44 ml h⁻¹. Theoretical calculations reveal that the Au (111) plane not only delivers a low energy barrier for the first hydrogenation of CO₂ molecule but also stabilizes the key *COOH intermediate, both of which are responsible for efficient electroreduction of CO₂ to CO.