Promoting Electrochemical CO2 Reduction to Formate Via Sulfur‐Assisted Electrolysis

Electrochemical CO2 reduction reaction ( CO2RR) provides a renewable approach to transform CO2 to produce chemicals and fuels. Unfortunately, it faces the challenges of sluggish CO(2)activation and slow water dissociation. This study reports the modification of Bi-based electrocatalyst by S, which leads to a remarkable enhancement in activity and selectivity during electrochemical CO2 reduction to formate. Based on comprehensive in situ examinations and kinetic evaluations, it is observed that the presence of S species over Bi catalyst can significantly enhance its interaction with K+(H2O)(n), facilitating fast dissociation of water molecules to generate protons. Further in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and in situ Raman spectroscopy measurements reveal that S modification is able to decrease the oxidation state of Bi active site, which can effectively enhance CO2 activation and facilitate HCOO* intermediate formation while suppressing competing hydrogen evolution reaction. Consequently, the S-modified Bi catalyst achieves impressive electrochemical CO2RR performance, reaching a formate Faradaic efficiency (FEformate) of 91.2% at a formate partial current density of approximate to 135 mA cm(-2) and a potential of -0.8 V versus RHE in an alkaline electrolyte.