An efficient precursor to synthesize various FeS2 nanostructures via a simple hydrothermal synthesis method

Abstract

Non-toxic and earth-abundant pyrite (FeS₂) is a promising photoelectric material for solar energy conversion and storage. In this study, an efficient FeS precursor was employed to synthesise successfully various shapes of pyrite FeS₂, such as nanopolyhedra, nanocubes, nanooctahedra, and irregular nanocrystals via a simple hydrothermal method by adjusting the reaction conditions. Pyrite FeS₂ nanopolyhedra and nanocubes were synthesised using the FeS precursor as the single iron source and thiourea (NH₂CSNH₂) as the sulphur source at various reaction temperatures. Nanooctahedra and irregular nanocrystals were obtained using sodium thiosulfate pentahydrate (Na₂S₂O₃·5H₂O) and sulphur powder as sulphur sources. The effects of polyvinylpyrrolidone content and the molar ratio of the FeS precursor to NH₂CSNH₂ on the formation of cubic shaped pyrite FeS₂ were investigated. The products were characterised by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible and Raman spectroscopy. The proposed facile hydrothermal method used an efficient FeS precursor as the iron source, which can be easily controlled to produce high-purity pyrite FeS₂ with desirable optical absorption properties.