Chlorine-Doped SnO2 Nanoflowers on Nickel Hollow Fiber for Enhanced CO2 Electroreduction at Ampere-Level Current Densities

Abstract

Renewable energy-driven electrochemical CO₂ 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 CO₂ electroreduction. Here we report a novel catalytic electrode comprising chlorine-doped SnO₂ nanoflowers arrayed on the exterior of three-dimensional nickel hollow fibers. This electrode demonstrates exceptional electrocatalytic performance for converting CO₂ to formate, achieving a remarkable formate selectivity of 99 % and a CO₂ single-pass conversion rate of 93 % at 2 A cm⁻². Furthermore, it exhibits excellent stability, maintaining a formate selectivity of above 94 % for 520 h at a current density of 3 A cm⁻². Experimental results combined with theoretical calculations confirm that the enhanced mass transfer facilitated by the hollow fiber penetration effect, coupled with the well-retained Sn⁴⁺ species and Sn−Cl bonds, synergistically elevates the activity of CO₂ conversion. The incorporation of chlorine into SnO₂ enhances electron transport and CO₂ adsorption, substantially lowering the reaction energy barrier for the crucial intermediate *OCHO formation, and boosting the formate production.