Direct Attack and Indirect Transfer Mechanisms Dominated by Reactive Oxygen Species for Photocatalytic H2O2 Production on g-C3N4 Possessing Nitrogen Vacancies

It is widely accepted that photogenerated holes are the only driving force for oxidizing an electron donor to form H + during photocatalytic H 2 O 2 production (PHP). Here, we use nitrogen deficiency carbon nitride as a model catalyst and propose several different reaction mechanisms of PHP based on the comprehensive analysis of experiment and simulation results. Nitrogen vacancies can serve as a center for oxidation, reduction, and charge recombination, promoting the generation of h +, •O 2 –, and 1 O 2, respectively, and thus induce H 2 O 2 generation through five different pathways. In particular, the 1 O 2 anchored on the catalyst surface can realize the indirect oxidation of isopropanol with the assistance of surrounding water molecules and produce H 2 O 2 with the lowest barrier. This work proves that H 2 O 2 can be generated through multiple pathways and highlights the main roles of 1 O 2, which are ignored by previous studies.