Promoted Hydrogen Peroxide Production from Pure Water on g-CN with Nitrogen Defects Constructed through Solvent-Precursor Interactions: Exploring a Complex Story in Piezo-Photocatalysis.

Hydrogen peroxide (HO) production via oxygen (O) reduction reaction (ORR) in pure water (HO) through graphitic carbon nitrides (g-CN)-based piezo-photocatalysts is an exciting approach in many current studies. However, the low Lewis-acid properties of g-CN limited the catalytic performance because of the low O adsorption efficacy. To overcome this challenge, the interaction of g-CN precursors with various solvents are utilized to synthesize g-CN, possessing multiple nitrogen-vacant species via thermal shocking polymerization. These results suggest that the lack of nitrogen in g-CN and the incident introduction of oxygen-functional groups enhance the Lewis acid-base interactions and polarize the g-CN lattices, leading to the enormous enhancement. Furthermore, the catalytic mechanisms are thoroughly studied, with the formation of HO proceeding via radical and water oxidation pathways, in which the roles of light and ultrasound are carefully investigated. Thus, these findings not only reinforce the potential view of metal-free photocatalysts, accelerating the understanding of g-CN working principles to generate HO based on the oxygen reduction and water oxidation reactions, but also propose a facile one-step way for fabricating highly efficient and scalable photocatalysts to produce HO without using sacrificial agents, pushing the practical application of in situ solar HO toward real-world scenarios.