Achieving pH‐universal electrosynthesis of formate under industrial‐grade current density by enriched selenium vacancies

Abstract

Electrosynthesis of formate via CO2 reduction (CO2ER) is of great significance for completing carbon cycle, however, low CO2 utilization efficiency caused by slow reaction kinetics greatly hinder its large‐scale application. Herein, we reported a ~50 nm‐thick SnSe2 nanosheets with enriched Se vacancies, which exhibits an excellent catalytic activity for pH‐universal formate electrosynthesis. In alkaline, neutral, and acidic electrolytes, this catalyst reached up to the maximum formate Faradaic efficiencies of 94.1%, 81.7%, and 78.1%, respectively. Under corresponding pH conditions, the maximum formate partial current densities achieved 800, 568, and 495 mA cm−2, respectively. Kinetic experiments combined with in situ electrochemical spectroscopy unveiled that the abundant Se vacancies promoted the dissociation of water to produce more protons, thereby accelerating the formation rate of key *OOCH intermediate. Theoretical calculations validated that the formation of enriched Sn active sites lowered the energy barrier for the *OOCH formation, eventually facilitating the formate electrosynthesis process.