The Electron Transport Regulation in Carbon Dots/In_2O_3 Electrocatalyst Enable 100 Selectivity for Oxygen Reduction to Hydrogen Peroxide

摘要

Direct electrosynthesis of hydrogen peroxide (H_2O_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_2O_3/CDs, and the influence of CDs on the ORR pathways of In_2O_3/CDs is also studied. The electron transfer kinetics on In_2O_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_2O_3 interface is obviously weakened after the addition of CDs, resulting in a high H_2O_2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H_2O_2, and the H_2O_2 selectivity of In_2O_3/CDs–10 is in close proximity to 100, which is much higher than that of pure In_2O_3 (72). This work will provide a new understanding and insight into addressing the challenge of low H_2O_2 selectivity for 2e? ORR catalysts.