Defective Indium/Indium Oxide Heterostructures for Highly Selective Carbon Dioxide Electrocatalysis

Electrochemical CO₂ reduction to fuels and chemicals is a promising approach for CO₂ utilization. Developing highly active, selective, and cost-effective electrocatalysts is the key to the large-scale application of this technology. Here, we report that defective indium/indium oxide heterostructures selectively catalyze CO₂ electroreduction into C₁ products in a broad potential range from -0.7 to -1.2 V vs RHE in aqueous media with the faradaic efficiency approaching 100%. This electrocatalyst enables an efficient CO₂-to-formate conversion with excellent selectivity (up to 93%), activity (up to 50.8 mA cm^-2), and durability (>25 h). The collaboration between metallic In and In oxide of the heterostructures attributes to the boosted electrochemical CO₂ reduction: Metallic In mainly facilitates formate production, while In oxide suppresses the competing hydrogen evolution reaction. This study highlights the integration of different functional components/defects into heterostructures as an effective strategy for enhancing CO₂ electrocatalysis.