In-situ reconstructed Cu-In2O3 electron-rich interfaces facilitate high selective CO2-to-CO conversion at low potentials

The electroreduction of CO 2 to CO is fundamentally hindered by sluggish COOH intermediate formation and the competing hydrogen evolution reaction. Herein, we show that this challenge can be addressed through the dynamic in-situ reconstruction of a CuO/In 2 O 3 precursor under electrochemical CO 2 reduction conditions. By employing in-situ electrochemical spectroscopy techniques in combination with theoretical calculations, we demonstrate that the presence of In 2 O 3 facilitates the complete reduction of CuO to metallic Cu. This in-situ reconstruction produces electron-rich Cu-In 2 O 3 interfaces, characterized by a reduced work function and an upshifted Cu 3 d -band center, which promote CO 2 activation and the formation of COOH/CO intermediates. Those interfacial properties lead to a pronounced electronic coupling that endows the electrocatalyst with high CO 2 -to-CO selectivity at low potentials. Specifically, the optimised Cu/In 2 O 3 achieves CO Faradaic efficiency above 90% across −0.5 to −0.9 V vs. the reversible hydrogen electrode, reaching 97.6% at −0.6 V in a H-type cell, and sustains a high CO selectivity of 96.0% even at an ultralow potential of −0.2 V in a flow-cell configuration. These findings underscore the crucial role of electron-rich interfaces in directing CO 2 reduction with exceptional selectivity and activity toward CO formation.