Defect-modulated oxygen adsorption and Z-scheme charge transfer for highly selective H2O2 photosynthesis in pure water

Solar-driven H 2 O 2 production provides an eco-friendly and scalable alternative to conventional anthraquinone processes. However, its efficiency has been limited by the inefficient charge separation and poor selectivity for the two-electron oxygen reduction reaction (2e - ORR). Here we report a Z-scheme heterojunction photocatalyst constructed by in-situ growth of sulfur-deficient ZnIn 2 S 4 nanosheets onto UiO-66-NH 2 (a zirconium-based metal-organic framework). This heterojunction promotes efficient charge separation while retaining strong redox capability, and sulfur vacancies regulate O 2 adsorption into a configuration that suppresses O-O bond cleavage and favors 2e - ORR. As a result, the composite achieves a high H 2 O 2 production rate of 3200 μmol g -1 h -1 with 94.3% selectivity in pure water under ambient air and visible light. A continuous-flow prototype exhibits stable performance for over 200 h, and the generated H 2 O 2 solution enables direct bacteria disinfection. Spectroscopic and theoretical analyses reveal the critical role of sulfur vacancies in optimizing O 2 activation. Our findings highlight a synergistic strategy of tuning charge dynamics and O 2 adsorption configurations for designing next-generation systems for sustainable H 2 O 2 production and water disinfection.