A Comparasion of Photocatalytic Activity Between FeS2, Ni-Doped FeS2 Nanoparticles and Un-Doped FeS2/rGO Composite

Un-doped and Ni-doped FeS2 nanoparticles (NPs) with a doping concentration of 4.0 at.% have been synthesized by a solvothermal method. The obtained materials have been characterized by means of XRD, SEM, BET, Raman and UV–VIS spectroscopy. The photocatalytic activity has been evaluated based on degrading methylene blue with thin films of the NPs under UV–VIS light irradiation. An important observation was that the activity increases in the sequence FeS2 NPs → Ni-doped FeS2 NPs → composite of FeS2 NPs/rGO. The enhanced energy gap and enlarged surface area, achieved by the Ni-doping and adding rGO were considered to be the main reason for the improved photocatalytic activity. Additionally, the mechanism of degradation has been studied using several scavengers. The photo-generated ·OH\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \cdot {\hbox{OH}} $$\end{document} and ·O2-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \cdot {\hbox{O}}_{2}^{ - } $$\end{document} have shown to be dominant radicals in the visible light MB degradation. The presented data strongly suggest that the composite of FeS2 NPs/rGO may be an efficient heterogeneous photo-catalyst for the degradation of the organic contaminant and water treatment. The proposed film forms of materials are promising for convenient reuse after a low-cost cleaning.