Promoted Hydrogen Peroxide Production from Pure Water on g-C 3 N 4 with Nitrogen Defects Constructed through Solvent-Precursor Interactions: Exploring a Complex Story in Piezo-Photocatalysis.

Hydrogen peroxide (H 2 O 2 ) production via oxygen (O 2 ) reduction reaction (ORR) in pure water (H 2 O) through graphitic carbon nitrides (g-C 3 N 4 )-based piezo-photocatalysts is an exciting approach in many current studies. However, the low Lewis-acid properties of g-C 3 N 4 limited the catalytic performance because of the low O 2 adsorption efficacy. To overcome this challenge, the interaction of g-C 3 N 4 precursors with various solvents are utilized to synthesize g-C 3 N 4 , possessing multiple nitrogen-vacant species via thermal shocking polymerization. These results suggest that the lack of nitrogen in g-C 3 N 4 and the incident introduction of oxygen-functional groups enhance the Lewis acid-base interactions and polarize the g-C 3 N 4 lattices, leading to the enormous enhancement. Furthermore, the catalytic mechanisms are thoroughly studied, with the formation of H 2 O 2 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-C 3 N 4 working principles to generate H 2 O 2 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 H 2 O 2 without using sacrificial agents, pushing the practical application of in situ solar H 2 O 2 toward real-world scenarios.