High-Performance Bi-Based Catalysts for CO₂ Reduction: In Situ Formation of Bi/Bi₂O₂CO₃ and Enhanced Formate Production.

The unavoidable self-reduction of Bismuth (Bi)-based catalysts to zero-valence Bi often results in detrimental adsorption of OCHO*, leading to unsatisfactory selectivity of HCOOH in the electroreduction of carbon dioxide (CO2). A novel Bi-tannin (Bi-TA) complex is developed, which undergoes in situ reconstruction into a Bi/Bi₂O₂CO₃ phase during CO2 reduction. This reconstructed catalyst exhibits high activity and selectivity, achieving a Faradaic Efficiency (FE) for formate production exceeding 90%, peaking at 96%. Operando spectroscopic and theoretical analyses reveal that the Biδ+ active site in Bi/Bi₂O₂CO₃ significantly enhances the formation of the OCHO* intermediate, crucial for formate production. The study offers a promising approach to overcoming the limitations of Bi-based catalysts in CO2 reduction to formate.