Electrosynthesis of a Defective Indium Selenide with 3D Structure on a Substrate for Tunable CO₂ Electroreduction to Syngas

Syngas (CO/H₂) is a feedstock for the production of a variety of valuable chemicals and liquid fuels, and CO₂ electrochemical reduction to syngas is very promising. However, the production of syngas with high efficiency is difficult. Herein, we show that defective indium selenide synthesized by an electrosynthesis method on carbon paper (γ-In₂Se₃/CP) is an extremely efficient electrocatalyst for this reaction. CO and H₂ were the only products and the CO/H₂ ratio could be tuned in a wide range by changing the applied potential or the composition of the electrolyte. In particular, using nanoflower-like γ-In₂Se₃/CP (F-γ-In₂Se₃/CP) as the electrode, the current density could be as high as 90.1 mA cm⁻² at a CO/H₂ ratio of 1:1. In addition, the Faradaic efficiency of CO could reach 96.5 % with a current density of 55.3 mA cm⁻² at a very low overpotential of 220 mV. The outstanding electrocatalytic performance of F-γ-In₂Se₃/CP can be attributed to its defect-rich 3D structure and good contact with the CP substrate.