Morphology-controlled And Photocatalytic Activity Of SnS₂ Nanostructures

Semiconductor photocatalysis, due to its high efficiency, cost-effectiveness, safety and simplicity, no secondary pollution and with the inexhaustible solar light as a driving force, has being become an effective green technology to solve environmental problems and energy crisis in the 21st century. Recently, controlling the morphology, size and component of the photocatalyst to improve its optical property and adsorption performance, has increased extensive attentions of the researchers and become one of the hot focus in the field of semiconductor photocatalysis. Typically, SnS2 which is commonly known as gold, has becoming a kind of potential and efficient photocatalyst, owing to its non-poisonous, insipidity, without excitant, rich source, good thermal stability and chemical stability, with the forbidden band width about 2.0 eV that can be good response to visible light. In this paper, we report a facile refluxing method and solvothermal method, without using any templates and surfactants, to synthesize SnS2 nanoparticles, nanosheets, nanoflowers and zinc doping of SnS2 nanosheets, and study the influence of the crystal morphology, structure and composition on the photocatalytic performance systematically. The main results are as follows:(1) SnS2 nanoparticles and nanosheets are successfully synthesized via a simple and convenient refluxing method and both SnS2 nanoparticles and nanosheets are hexagonal SnS2 phase. As the refluxing method is a dissolution and recrystallization reaction process, the temperature will impact the growth process and the crystallization of SnS2. Therefore, SnS2 nanoparticles synthesized at low temperature create a high density of sulfur vacancies, which can impel the charge separation and transportation, leading to enhanced visible light photocatalytic activities; while SnS2 nanosheets synthesized at high temperature show high adsorption capacities owing to the special morphology and large specific surface area.(2) SnS2 nanoflowers and nanosheets are successfully prepared by a facile solvothermal method and all samples with hexagonal SnS2 phase show high degree of crystallinity. SnS2 nanoflowers are synthesized by using ethylene glycol as solvent. With the concentration of the reactants increasing, the size of the sample becomes small and gets better adsorption performance become of the special morphology. However, SnS2 nanosheets are fabricated by employing water as solvent show enhanced photocatalytic activity.(3) Zinc doping SnS2 nano structures is successfully prepared by hydrothermal method with enhanced absorption intensity in the visible region. The photoinduced decomposition of methylene blue under the condition of visible light are performed in order to analyze the photocatalytic property of the samples. The experiment results show that the doping of the sample has good catalytic activity and commercial potential value. This is because the doping of the sample can produce more rapid separation photogenerated electron-hole pairs and·OH under visible light irradiation, which can improve the photocatalytic activity of tin disulfide.