Unveiling in situ evolved In/In2O3−x heterostructure as the active phase of In2O3 toward efficient electroreduction of CO2 to formate

Abstract Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts for CO2 electroreduction (CO2ER). And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable. Here, In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition. In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous-In2O3−x heterostructure (In/In2O3−x). In/In2O3−x acts as the real active phase with Faradaic efficiency of ∼89.2% for the formate, outperforming In (∼67.5%). The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In/In2O3−x heterostructure. Impressively, formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In/In2O3−x‖Ni2P two-electrode electrolyzer.