Halogen‐Incorporated Sn Catalysts for Selective Electrochemical CO2 Reduction to Formate

Abstract Electrochemically reducing CO 2 to valuable fuels or feedstocks is recognized as a promising strategy to simultaneously tackle the crises of fossil fuel shortage and carbon emission. Sn‐based catalysts have been widely studied for electrochemical CO 2 reduction reaction (CO 2 RR) to make formic acid/formate, which unfortunately still suffer from low activity, selectivity and stability. In this work, halogen (F, Cl, Br or I) was introduced into the Sn catalyst by a facile hydrolysis method. The presence of halogen was confirmed by a collection of ex situ and in situ characterizations, which rendered a more positive valence state of Sn in halogen‐incorporated Sn catalyst as compared to unmodified Sn under cathodic potentials in CO 2 RR and therefore tuned the adsorption strength of the key intermediate (*OCHO) toward formate formation. As a result, the halogen‐incorporated Sn catalyst exhibited greatly enhanced catalytic performance in electrochemical CO 2 RR to produce formate.