A carbon dot-based metal-free photocatalyst enables O-2 to serve as both a reactant and electron sink for enhancing H2O2 photoproduction

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 degrees C) expanded the role of oxygen, showing high performance in H2O2 photoproduction with a yield of up to 2667 mu mol 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 O-2 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.