Synthesis of novel Sn<inf>1-x</inf>Fe<inf>x</inf>S nanocomposites with narrow band gap energy for absorption of full broad spectrum

Abstract

SnS is a low cost photocatalyst for solar energy conversion due to its narrow bandgap energy. However, the fast recombination of the electron-hole pair reduces its reactivity under light radiation. In this novel research, a series of Sn1-xFexS heterostructures containing various proportions of Fe2+ ions are synthesized by a facile hydrothermal route using SnCl2 as a low cost and non-toxic precursor. The as-synthesized samples are well characterized using XRD, DRS, HRTEM, XPS and PL analysis. Fe2+ ions alter the optical properties, and the band gap energy of SnS is influenced by the concentration of Fe in each nanocomposite. It is obvious to notice that the increase in the concentration of Fe in the nanocomposites is accompanied by an increase in the recombination rate of the charge carriers, which reduces the photocatalytic efficiency of Sn1-xFexS compared with pristine SnS. The decomposition of rhodamine B dye under a UV mercury lamp is carried out to compare the efficiency of the as-synthesized samples and to explore a clear relationship between optical properties and the photodegradation efficiency. The removal of RhB dye is carried out through a tandem adsorption-photocatalytic process on the surface of pristine SnS nanoparticles. Nevertheless, the removal of RhB dye on the nanocomposite surface is performed through a predominant photocatalytic process, indicating that Fe2+ ions are strongly adsorbed on the active sites of SnS hindering the adsorption process. The exceptional photocatalytic efficiency results from the strong absorbability of SnS to a full absorption spectrum due to its narrow band gap energy.