FeOCl/MOF-derived In2S3 photocatalysts with high H2O2 adsorption: Degradation mechanism, H2O2 activation process.

ABSTRACT

The FeOCl-based photo-Fenton heterojunction catalyst holds great promise for effective water pollution treatment. A novel heterojunction FeOCl/MOF-In2S3 (F/M-I) was fabricated by coating hollow MOF-In2S3 nanoflowers onto the surface of FeOCl. Under the optimal conditions, the maximum photo-Fenton degradation rate constants of FeOCl/MOF-In2S3 for oxytetracycline (OTC) within 20 min is 0.88192 L mg-1·min-1, which are 3.2 and 2.5 times that of pure FeOCl (0.27357 L mg-1·min-1) and MOF-In2S3 (0.35222 L mg-1·min-1). Density functional theory (DFT) results confirm that the electron-rich nature of MOF-In2S3 accelerates the cycle between Fe (III)/Fe (II)of FeOCl, promoting H2O2 adsorption by FeOCl/MOF-In2S3 and generating more hydroxyl radicals (·OH) for pollutant degradation. Based on the results of DFT, combined with the results of the reactive oxidation species scavenger (ROSs), electron paramagnetic resonance (EPR) and Mott-Schottky curves, the separation and transfer behavior of photoexcited charges in FeOCl/MOF-In2S3 heterojunction and the possible photocatalytic degradation mechanism were investigated. Finally, a Z-scheme heterostructure is proposed to elucidate the catalytic mechanism. This study provides a new perspective on designing and synthesizing semiconductor materials for water treatment by photo-Fenton catalysis.