The conversion of superoxide radical (·O2−) to hydrogen peroxide (H2O2) is critical in the photocatalytic formation of H2O2 via the sequential two-step single-electron oxygen reduction mechanism. Providing a high concentration of ·O2− 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 ·O2−. To this end, a concept about local ·O2− enrichment catalyst surface was proposed in this study and achieved in an innovative PSI/C3N4 photocatalyst. The results of theoretical calculations and temperature-dependent photocatalytic studies indicate that PSI on the C3N4surface can serve as a diffusion buffer for ·O2−, capturing them through Van der Waals interactions and separating them by energy perturbations. As a result, a local enrichment of ·O2− was established on the PSI/C3N4 surface during photocatalysis, strengthening the photocatalytic conversion of ·O2− to H2O2, thus allowing the PSI/C3N4-4 photocatalyst to produce H2O2 at a rate of approximately 2.4 and 2.65 times greater than pure C3N4 under visible light and LED irradiation, respectively. This study presents a promising strategy for enhancing photocatalytic H2O2 production efficiency by selectively enriching ·O2− on the catalyst surface.