A carbon dot-based metal-free photocatalyst enables O2 to serve as both a reactant and electron sink for enhancing H2O2 photoproduction

Abstract

Photocatalytic oxygen reduction via the two-electron route is the cleanest and greenest method for the production of hydrogen peroxide (H₂O₂). However, in most catalytic systems, the function of oxygen is simply to participate in the reaction as a reactant. Herein, a metal-free catalyst (DEX-160, derived from the hydrothermal treatment of dextran at 160 °C) expanded the role of oxygen, showing high performance in H₂O₂ photoproduction with a yield of up to 2667 μmol g⁻¹ h⁻¹. Carbon dots generated on the surface of DEX-160 promote the separation and transfer of photo-induced charges. The in situ transient photo-induced voltage and photoelectrochemistry tests show that O₂ served as both a reactant and an electron sink to enhance the H₂O₂ photoproduction in the photocatalytic process of DEX-160. This study provides new insight for understanding the role of oxygen and the carbon dot-assisted metal-free photocatalyst for H₂O₂ evolution.