Inhibition of superoxide radical diffusion by Van der Waals forces for boosting photocatalytic H2O2 production

The conversion of superoxide radical (·O 2 − ) to hydrogen peroxide (H 2 O 2 ) is critical in the photocatalytic formation of H 2 O 2 via the sequential two-step single-electron oxygen reduction mechanism. Providing a high concentration of ·O 2 − is an effective approach to promoting this process in terms of chemical kinetics. It is, however, extremely challenging to implement this idea in the photocatalytic solution due to the limited lifespan of ·O 2 − . To this end, a concept about local ·O 2 − enrichment catalyst surface was proposed in this study and achieved in an innovative PSI/C 3 N 4 photocatalyst. The results of theoretical calculations and temperature-dependent photocatalytic studies indicate that PSI on the C 3 N 4   surface can serve as a diffusion buffer for ·O 2 − , capturing them through Van der Waals interactions and separating them by energy perturbations. As a result, a local enrichment of ·O 2 − was established on the PSI/C 3 N 4 surface during photocatalysis, strengthening the photocatalytic conversion of ·O 2 − to H 2 O 2 , thus allowing the PSI/C 3 N 4 -4 photocatalyst to produce H 2 O 2 at a rate of approximately 2.4 and 2.65 times greater than pure C 3 N 4 under visible light and LED irradiation, respectively. This study presents a promising strategy for enhancing photocatalytic H 2 O 2 production efficiency by selectively enriching ·O 2 − on the catalyst surface.