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 <i>Escherichia coli</i> (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.