Fe doping in In2S3 hollow nanotubes for efficient photo-Fenton degradation of emerging organic pollutants

The primary factor in the application of heterogeneous Fenton catalysts for practical wastewater treatment lies in the effective activation of hydrogen peroxide (H2O2). Herein, a Fe-doped In2S3 hollow nanotube catalyst (Fe-In2S3) is developed and optimized to enable visible light-induced H2O2 activation aimed at the efficient degradation of organic pollutants. Computational analysis indicates that Fe doping aids in the adsorption and catalytic decomposition of H2O2, facilitating homolytic cleavage and resulting in the generation of highly oxidative hydroxyl radicals (•OH). Moreover, Fe doping improves the light absorption capability of In2S3 and fosters the separation of photogenerated charge carriers. The ongoing production of photoexcited electrons supports the valence cycling of Fe species, maintaining elevated catalytic activity. In experiments involving tetracycline (TC) degradation with Fe-In2S3, the observed pseudo-first-order kinetic constant (kobs) is 5.5 times greater than that of the single Fenton reaction after visible light exposure. Within the photo-Fenton system, the kobs of Fe-In2S3 is 0.151 min−1, which is 6.5 times greater than that of In2S3. Owing to the formation of multiple active species during the photo-Fenton catalytic processes, Fe-In2S3 demonstrates remarkable degradation efficiencies against a range of organic contaminants typically found in wastewater.