Atomically Dispersed Magnesium Centers on Carbon Nitride for H2O2 Production and Synergistic In Situ Water Disinfection.

Safe drinking water is vital to human health and developing efficient water disinfection technologies, especially for resource-limited regions, is a pressing environmental challenge. Photocatalytic in situ generation of hydrogen peroxide (H2O2) offers a promising, sustainable approach for water disinfection. However, its practical implementation is restricted by reliance on sacrificial electron donors. In this work, we address this limitation through an innovative design of a photocatalyst by embedding atomically dispersed magnesium (Mg) sites within ultrathin graphitic carbon nitride (g-C3N4) nanosheets. Such a design draws inspiration from natural systems, specifically the light-harvesting function of chlorophyll and the catalytic efficiency of Mg-containing enzymatic cofactors. The engineered catalyst achieves a remarkable H2O2 production rate of 889 μmol g-1 h-1 under visible light irradiation without sacrificial agents. Comprehensive mechanistic studies, including in situ Fourier-transform infrared spectroscopy, pump-probe spectroscopy, and density functional theory calculations, reveal that the Mg sites function as effective proton reservoirs, facilitating water activation and enabling efficient two-electron oxygen reduction for H2O2 formation. Importantly, such a well-designed system demonstrates exceptional in situ bactericidal performance, achieving complete disinfection of model Escherichia coli (99.9999% sterilization efficiency) within 80 min. This nature-inspired catalyst design not only represents an advance in green synthesis methods for single-atom catalysts but also highlights significant potential for environmentally benign water disinfection, addressing critical global needs in water safety and sustainability.