Interfacial Interaction‐Mediated Regulation of Metal Oxidation States for Enhanced CO ₂ Reduction

Abstract In the field of electrocatalytic CO₂ reduction, bismuth (Bi) and its compounds have garnered significant attention due to their excellent selectivity for formate production and low toxicity. However, their practical application is limited by sluggish kinetics and high overpotentials. In this study, a novel vanadium oxynitride (VON)‐ Bi hybrid material is developed that enables precise control of in situ Bi–oxygen (O) formation during a topochemical process to regulate Bi oxidation states effectively. The unique interfacial interaction facilitates the formation of abundant Bi─O bonds in metallic Bi, successfully addressing the challenge of maintaining the intrinsic catalytic sites at the core of Bi nanoparticles while simultaneously enhancing both the catalytic kinetics and thermodynamics at the border. As a result, the VON‐Bi catalyst effectively addresses the issue of sluggish kinetics associated with Bi metal, achieving an impressive Faradaic efficiency of 97.11% for formate production. Additionally, it exhibits outstanding scalability and durability in flow‐cell testing at 100 mA cm −2 for 120 h, outperforming the most reported bismuth oxides and their derivatives. This strategy can be extended to other systems such as VON‐nickle and VON‐copper, highlighting its versatility in designing efficient catalysts through interfacial metal‐oxygen interactions.