Photocatalytic properties of Cu2(Fe,Mn)SnS4 microspheres synthesized via hydrothermal method

The most industrial activities, that require organic dye materials for their applications, release a remarkable fraction of effluent water. As a result, serious environmental problems emerge due to the toxicity of many compounds which these industrial processes produce. The development of inexpensive and green methods for degradation of such organic dye laden water constitutes a landmark for the mitigation or even the elimination of the industrial sewage. Among many strategies, photocatalysis is regarded as the most viable one due to its usage of sunlight to decomposing organic pollutants.

The unlimited applications of nanocrystalline semiconductor materials in all sorts of technological fields, whether photochemical, biological, photovoltaic or photocatalysis have pushed to develop a new assortment of materials featuring novel properties for advanced applications. Semiconductor properties of stannite Cu₂FeSnS₄ make it a potential candidate for application in photocatalytic industry. In nature, it is a common sulfide mineral which is formed as a result of hydrothermal processes. Its crystal structure allows for numerous substitutions including replacement of Fe by Mn.

In this report, the photocatalytic activity of  Cu₂FeSnS₄ (CFTS) and Cu₂MnSnS₄ (CMTS) synthetic microspheres for degradation of environment polluting dye such as methylene blue (MB) has been explored under UV light illumination. The unique morphology of the as-synthesized nanomaterial is expected to play a major role in tailoring the optical and electrical properties for the possible photo-voltaic application. The photocatalytic activity shows the potential use of this material as an efficient photocatalyst for wastewater treatment.

Modified stannite was synthesized by hydrothermal method using reactions of metal salts and sulfur in hot ethylene glycol at presence PVP solution in an autoclave at 195^oC. The crystallinity, structural features, morphology and chemical composition were investigated using XRD, Raman, FTIR, and SEM - EDS. Synthetic Cu₂(Fe,Mn)SnS₄ solid solutions are composed of spheres 1 – 1.5 µm in size, with rough surface and concentric internal structure. The structure matches hexagonal stannite. The promising optoelectrical and photocatalytic properties of CFTS and CMTS microspheres make them a potential candidate for photovoltaics as well as for effective wastewater treatment, providing further study has to be carried out to improve specific properties.

Financial support for the research was provided by Polish Ministry of Higher Education grant No. DI2016 004946 under "Diamond Grant" program.