An ultrathin carbon-shelled indium oxide catalyst for electroreduction of CO2 to formate at ampere-level current density

Abstract

Electrochemical carbon dioxide reduction reaction (eCO₂RR) offers a sustainable synthesis of high-value formate, yet its practical application is still limited by the scarcity of catalysts that combine high efficiency with long-term operational stability. Herein, we report an ultrathin (ca. 1 nm) carbon-shelled indium oxide catalyst (In₂O₃@C) that enables efficient and stable eCO₂RR to formate. The carbon shell not only effectively suppresses the corrosion of amphoteric indium oxide in alkaline electrolyte, significantly enhancing the long-term durability of the catalyst, but also regulates the adsorption configuration of the key intermediate *OCHO, optimizing the electronic structure and reducing the energy barrier for its formation, thereby accelerating the reaction kinetics. The synergistic multiple effects enable In2O3@C to maintain formate Faradaic efficiencies of over 90% within a wide potential window (-1.1 to -1.9 V vs. reversible hydrogen electrode) and achieve a peak current density of nearly 1 A cm^-2 in a flow cell. Notably, no significant performance degradation was observed during a continuous 110-hour electrolysis test, well demonstrating its excellent stability. This study not only proposes a reliable strategy for enhancing the durability of eCO₂RR catalysts but also establishes a universal material design paradigm that is expected to be widely applied in the performance optimization of traditional catalytic systems.