In₂O₃/Bi₂O₃ interface induces ultra-stable carbon dioxide electroreduction on heterogeneous InBiO_x catalyst

The electrochemical reduction of CO₂ (ERCO₂) has emerged as one of the most promising methods for achieving both renewable energy storage and CO₂ recovery. However, achieving both high selectivity and stability of catalysts remains a significant challenge. To address this challenge, this study investigated the selective synthesis of formate via ERCO₂ at the interface of In₂O₃ and Bi₂O₃ in the InBiO₆ composite material. Moreover, InBiO₆ was synthesized using indium-based metal-organic frameworks as precursor, which underwent continuous processing through ion exchange and thermal reduction. The results revealed that the formate Faradaic efficiency (FE_formate) of InBiO₆ reached nearly 100 % at -0.86 V vs. reversible hydrogen electrode (RHE) and remained above 90 % after continuous 317-h electrolysis, which exceeded those of previously reported indium-based catalysts. Additionally, the InBiO₆ composite material exhibited an FE_formate exceeding 80 % across a wide potential range of 500 mV from -0.76 to -1.26 V vs. RHE. Density-functional theory analysis confirmed that the heterogeneous interface of InBiO₆ played a role in achieving optimal free energies for *OCHO on its surface. Furthermore, the addition of Bi to the InBiO₆ matrix facilitated electron transfer and altered the electronic structure of In₂O₃, thereby enhancing the adsorption, decomposition, and formate production of *OCHO.