Solar-to-hydrogen peroxide conversion of photocatalytic carbon dots with anthraquinone: Unveiling the dual role of surface functionalities

Solar-driven photocatalytic production of hydrogen peroxide (H2O2) requires only sunlight, oxygen, and water, making it a green and sustainable alternative to conventional H2O2 production processes. We present photo-catalytic carbon dots (CDs) as a new candidate for high-performance H2O2 production. Owing to the generation of an excellent charge carrier and the presence of various oxygen-containing functional groups, CDs showed an outstanding H2O2 production capability of 609.4 mu mol g(-1) h(-1) even in the absence of an electron donor, demonstrating promising self-electron-donating capabilities. Hydroxyl groups on their surface, in particular, serve a dual role as photocatalytic active sites and as electron and proton donors toward the oxygen reduction reaction (ORR). The photocatalytic activity of CDs was significantly improved to 1187.8 mu mol g(-1) by functionalizing their surfaces with anthraquinone (AQ) as a co-catalyst; it promoted the charge carrier separation and electrochemically favored the two-electron pathway of ORR. These carbon-based metal-free nanohybrids that are a unique combination of CDs and AQ could offer insights into designing efficient photocatalysts for future solar-to-H2O2 conversion systems.