Unveiling phase-selective a- and #-Bi2O3-derived electrocatalysts for CO2 electroreduction

Phase engineering to modulate the physicochemical properties of nanostructured metal oxides has shown great potential in electrocatalysis but has rarely been studied for the electrochemical CO2 reduction reaction (CO2RR). Herein, we have prepared a-Bi2O3 and #-Bi2O3 through a facile method with controllable phase transition. Compared to a-Bi2O3, the phase-difference-induced physicochemical property change of #-Bi2O3 makes it have better CO2 chemisorption capacity and water dissociation ability than a- Bi2O3. This favors fast reaction kinetics for formate formation and leads to better CO2RR performance of #-Bi2O3 than a-Bi2O3, achieving a maximum Faradaic efficiency of 98.1% at -1.1 V and good stability of 36 h. Computational results further unravel the exothermic processes of the key intermediate *OCHO formation and water dissociation on #-Bi2O3. This work underscores the effectiveness of phase engineering of metal oxides in the CO2RR and pro-vides more opportunities for the intellectual design of highly efficient catalysts to achieve environmental sustainability.