Development of hydrothermal carbonaceous carbon/NH2-MIL-101(Fe) composite photocatalyst with in-situ production and activation of H2O2 capabilities for effective sterilization

Photocatalytic production of H 2 O 2 has garnered significant attention, but the use of sacrificial reagents in H 2 O 2 photosynthesis and the subsequent limited H 2 O 2 activation efficiency would impede its practical application in water decontamination. In this work, hydrothermal carbonaceous carbon/NH 2 -MIL-101(Fe) (abbreviated as HTC-cf/NMIL-101(Fe)) heterojunction was fabricated through a solvothermal strategy, and serving as a self-sufficient photo-Fenton-like catalyst to in-situ generate and activate H 2 O 2 . Hydrothermal carbonaceous carbon derived from cost-effective waste coffee grounds, serving as a green and sustainable photocatalyst, demonstrated high H 2 O 2 production rate of 612 μmol/g/h without the need for sacrificial reagents or aeration assistance. Moreover, the excellent self-sufficient photo-Fenton activity for HTC-cf/NMIL-101(Fe) can be obtained, which ascribed to the synergistic effect of self-generated H 2 O 2 production as well as the in-situ catalytic H 2 O 2 decomposition of • OH by Fe species in NMIL-101(Fe) and photogenerated electrons. The optimized HTC-cf/NMIL-101(Fe) photocatalyst showed simultaneous improvements in both H 2 O 2 production and activation capabilities. Impressively, the effective circulation of Fe 3+ /Fe 2+ in NMIL-101(Fe), aided by photogenerated electrons, results in a 5-fold increase toward H 2 O 2 decomposition rate constant (K d ) compared to HTC-cf alone under light irradiation in open-air conditions. The enhanced charge separation and appropriate band structure of HTC-cf/NMIL-101(Fe) photocatalyst assured the high selectivity of two-electron O 2 -reduction to H 2 O 2 . HTC-cf/NMIL-101(Fe) displayed excellent photocatalytic sterilization efficiency against E. coli and S. aureus under visible light, and its sterilization application in actual water was also demonstrated. Notably, the adaptability of this system to ambient conditions, including open-air atmosphere, non-sacrificial reagents, and low leaching of Fe ions, highlights the promising practical utility of the HTC-cf/NMIL-101(Fe) photocatalyst.