Efficient Hydrogen Peroxide Photosynthesis over CdS/COF for Water Disinfection: The S-Scheme Pathway, Oxygen Adsorption, and Reactor Design

Solar-driven photocatalytic hydrogen peroxide (H₂O₂) production presents a promising avenue for achieving sustainable water disinfection. However, the development of a robust and durable system for practical applications remains a notable and unresolved challenge. Herein, a star photocatalyst, the covalent organic frameworks (COFs), was modified with CdS for boosting environmentally benign H₂O₂ synthesis. Under simulated sunlight and without sacrificial reagents, the composite material exhibited a boosting capacity for H₂O₂ production, which was attributable to the establishment of a “step” (S)-scheme transfer pathway and facilitation of adequate oxygen diffusion. Nevertheless, it was found that photocatalytically derived H₂O₂ alone exhibited inefficient disinfection performance, whereas the addition of Fe(II) allowed rapid inactivation of Escherichia coli, emphasizing the pivotal importance of integrating photocatalysis and Fenton reactions within the photocatalytic H₂O₂ production system. Furthermore, a dual-compartment reactor, employing a semipermeable membrane, was devised to spatially segregate photocatalysts from microorganisms. Such an operation mode enabled H₂O₂ diffusion from the photocatalytic compartment to the microbial compartment, thereby achieving a “long-distance” sterilization manner and simultaneous consummating recovery strategy of the photocatalysts. This study not only provides a paradigmatic approach for boosting the production of H₂O₂ from a COF-based material but also illuminates an innovative technological option for sustainable photocatalytic-based water disinfection.