The Electron Transport Regulation in Carbon Dots/In2O3 Electrocatalyst Enable 100% Selectivity for Oxygen Reduction to Hydrogen Peroxide

Abstract Direct electrosynthesis of hydrogen peroxide (H 2 O 2 ) via two‐electron pathway oxygen reduction reaction (2e − ORR) is crucially essential for a sustainable green economy. However, catalysts inevitably undergo four‐electron pathway oxygen reduction reaction (4e − ORR), resulting in low selectivity and economic benefits. The current challenge is to provide a feasible design strategy for obtaining satisfactory 2e − ORR catalysts with high selectivity. In this work, carbon dots (CDs) act as a cocatalyst to regulate the electron transport kinetics of In 2 O 3 /CDs, and the influence of CDs on the ORR pathways of In 2 O 3 /CDs is also studied. The electron transfer kinetics on In 2 O 3 /CDs composites are studied and analyzed using the transient photo‐induced voltage (TPV) technology. Combining the TPV results and kinetics analysis, it is shown that the electron transport on the In 2 O 3 interface is obviously weakened after the addition of CDs, resulting in a high H 2 O 2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H 2 O 2 , and the H 2 O 2 selectivity of In 2 O 3 /CDs–10 is in close proximity to 100%, which is much higher than that of pure In 2 O 3 (72%). This work will provide a new understanding and insight into addressing the challenge of low H 2 O 2 selectivity for 2e − ORR catalysts.