Chlorine-Doped SnO Nanoflowers on Nickel Hollow Fiber for Enhanced CO Electroreduction at Ampere-Level Current Densities.

Renewable energy-driven electrochemical CO reduction has emerged as a promising technology for a sustainable future. However, achieving efficient production of storable liquid fuels at ampere-level current densities remains a significant hurdle in the large-scale implementation of CO electroreduction. Here we report a novel catalytic electrode comprising chlorine-doped SnO nanoflowers arrayed on the exterior of three-dimensional nickel hollow fibers. This electrode demonstrates exceptional electrocatalytic performance for converting CO to formate, achieving a remarkable formate selectivity of 99 % and a CO single-pass conversion rate of 93 % at 2 A cm. Furthermore, it exhibits excellent stability, maintaining a formate selectivity of above 94 % for 520 h at a current density of 3 A cm. Experimental results combined with theoretical calculations confirm that the enhanced mass transfer facilitated by the hollow fiber penetration effect, coupled with the well-retained Sn species and Sn-Cl bonds, synergistically elevates the activity of CO conversion. The incorporation of chlorine into SnO enhances electron transport and CO adsorption, substantially lowering the reaction energy barrier for the crucial intermediate *OCHO formation, and boosting the formate production.