Promoting Electrochemical CO<sub>2</sub> Reduction to Formate via Sulfur‐Assisted Electrolysis
Yuhang Liu, Zhiming Wei, Xiaozhi Su, Xiuwen Shi, Lingyue Liu, Tianyu Wang, Xueting Xu, Ming Zhao, Yueming Zhai, Hong Bin Yang, Bin Liu
Abstract
Abstract Electrochemical CO 2 reduction reaction (CO 2 RR) provides a renewable approach to transform CO 2 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 CO 2 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 + (H 2 O) 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 CO 2 activation and facilitate HCOO * intermediate formation while suppressing competing hydrogen evolution reaction. Consequently, the S‐modified Bi catalyst achieves impressive electrochemical CO 2 RR performance, reaching a formate Faradaic efficiency (FE formate ) of 91.2% at a formate partial current density of ≈135 mA cm −2 and a potential of −0.8 V versus RHE in an alkaline electrolyte.