In-situ structural evolution of Bi₂O₃ nanoparticle catalysts for CO₂ electroreduction

Abstract Under the complex external reaction conditions, uncovering the true structural evolution of the catalyst is of profound significance for the establishment of relevant structure-activity relationships and the rational design of electrocatalysts. Here, the surface reconstruction of the catalyst was characterized by ex-situ methods and in-situ Raman spectroscopy in CO₂ electroreduction. The final results showed that the Bi₂O₃ nanoparticles were transformed into Bi/Bi₂O₃ two-dimensional thin-layer nanosheets (NSs). It is considered to be the active phase in the electrocatalytic process. The Bi/Bi₂O₃ NSs showed good catalytic performance with a Faraday efficiency (FE) of 94.8% for formate and a current density of 26 mA cm^-2 at -1.01 V. While the catalyst maintained a 90% FE in a wide potential range (-0.91 V to -1.21 V) and long-term stability (24 h). Theoretical calculations support the theory that the excellent performance originates from the enhanced bonding state of surface Bi-Bi, which stabilized the adsorption of the key intermediate OCHO and thus promoted the production of formate.