Modulation of the electronic structure of metallic bismuth catalysts by cerium doping to facilitate electrocatalytic CO2 reduction to formate

Abstract

Metallic bismuth (Bi) can maintain a stable structure at high reduction potential during the CO₂ reduction reaction (CO₂RR) process; however, it is limited by its relatively unfavorable catalytic activity. To address this limitation, an effective strategy of electronic structure modulation can be employed to optimize the adsorption energy of reaction intermediates for enhancing CO₂RR performance. Based on this principle, we have developed a highly efficient and stable electrocatalyst comprising metallic Ce-doped Bi(0) nanoparticles encapsulated in a porous carbon framework. This catalyst exhibits a substantial improvement in CO₂RR activity compared with its undoped counterpart, driving a current density of 13.7 mA cm⁻² with a faradaic efficiency of 97.2% for formate production at −1.1 V versus the reversible hydrogen electrode. Furthermore, long-term stability was achieved with an average faradaic efficiency close to 94% during a 48 hour electrocatalytic test. Density functional theory calculations, combined with the in situ attenuated total reflectance infrared (ATR-IR) spectroscopic study, indicate that the doping of Ce enriches the electron density around Bi, consequently enhancing the binding energy between the Bi active centers and *OCHO intermediates, thereby lowering the energy barrier for the CO₂RR to formic acid.