Rational Design of a Hierarchical Tin Dendrite Electrode for Efficient Electrochemical Reduction of CO2

Abstract Catalysis is a key technology for the synthesis of renewable fuels through electrochemical reduction of CO 2 . However, successful CO 2 reduction still suffers from the lack of affordable catalyst design and understanding the factors governing catalysis. Herein, we demonstrate that the CO 2 conversion selectivity on Sn (or SnO x /Sn) electrodes is correlated to the native oxygen content at the subsurface. Electrochemical analyses show that the reduced Sn electrode with abundant oxygen species effectively stabilizes a CO 2 .− intermediate rather than the clean Sn surface, and consequently results in enhanced formate production in the CO 2 reduction. Based on this design strategy, a hierarchical Sn dendrite electrode with high oxygen content, consisting of a multi‐branched conifer‐like structure with an enlarged surface area, was synthesized. The electrode exhibits a superior formate production rate (228.6 μmol h −1 cm −2 ) at −1.36 V RHE without any considerable catalytic degradation over 18 h of operation.