• • Achieved a photocatalytic H2O2 production rate of 2.399 mmol g−1 h−1 under visible-light irradiation, a 12-fold enhancement over pristine g-C3N4, demonstrating the potential for scalable solar-driven H2O2 synthesis.
• • H2O2 selectivity reached 87.4%, indicating that the Zn/VN-CN catalyst effectively suppresses the competing 4-electron ORR pathway, which is critical for industrial adoption where product purity is paramount.
• • Nitrogen vacancy engineering downshifts the d-band center of Zn sites, moderating O2 adsorption strength and lowering the activation energy barrier for *H2O2 formation, as confirmed by combined experimental and theoretical studies.
• • The Zn-N3 sites serve as highly active reaction centers, with nitrogen vacancies increasing charge density, thereby enhancing charge separation and photocatalytic efficiency, a key factor for practical solar-to-chemical conversion.