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

Abstract

Photocatalytic production of H2O2 has garnered significant attention, but the use of sacrificial reagents in H2O2 photosynthesis and the subsequent limited H2O2 activation efficiency would impede its practical application in water decontamination. In this work, hydrothermal carbonaceous carbon/NH2-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 H2O2. Hydrothermal carbonaceous carbon derived from cost-effective waste coffee grounds, serving as a green and sustainable photocatalyst, demonstrated high H2O2 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 H2O2 production as well as the in-situ catalytic H2O2 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 H2O2 production and activation capabilities. Impressively, the effective circulation of Fe3+/Fe2+ in NMIL-101(Fe), aided by photogenerated electrons, results in a 5-fold increase toward H2O2 decomposition rate constant (Kd) 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 O2-reduction to H2O2. 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.