FeOCl/MOF-derived InS Photocatalysts with High HO Adsorption: Degradation Mechanism, HO Activation Process

The FeOCl-based photo-Fenton heterojunction catalyst holds great promise for effective water pollution treatment. A novel heterojunction FeOCl/MOF-InS (F/M-I) was fabricated by coating hollow MOF-InS nanoflowers onto the surface of FeOCl. Under the optimal conditions, the maximum photo-Fenton degradation rate constants of FeOCl/MOF-InS for oxytetracycline (OTC) within 20 min is 0.88192 L mg·min, which are 3.2 and 2.5 times that of pure FeOCl (0.27357 L mg·min) and MOF-InS (0.35222 L mg·min). Density functional theory (DFT) results confirm that the electron-rich nature of MOF-InS accelerates the cycle between Fe (III)/Fe (II)of FeOCl, promoting HO adsorption by FeOCl/MOF-InS 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-InS 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.