A review of visible light active SnS photocatalyst for efficient photocatalytic water purification

Abstract

Due to the complexity of the existing treatment process, illegally releasing chemical-laden wastewater into the nearby rivers and lakes has become the cheapest way for textile dying factories to dispose of it. The untreated harmful synthetic textile dyes released into natural water bodies has created irrecoverable environmental problems and health hazards in several parts of the world. Degradation and complete mineralization of these dyes present in real wastewater are still challenging, due to the presence of several other contaminants. This comprehensive review gives a brief overview of the actual textile effluent treatment processes such as adsorption, floatation, Fenton treatment, Ozonation presently in use and their limitations. Merits of SnS as a material for practical use in natural solar energy driven photocatalysis of toxic dyes are discussed. Owing to their specific surface area and charge separation capabilities, nanostructures, composites and heterostructures generally shows superior catalytic performance over pristine materials. In this review, SnS based photocatalysts are classified into three different categories, namely: nanoparticles and structures, nanocomposites and heterostructures for better comparison of their catalytic performance analysis of the reported results. In each category, the focus of the current review is strategies employed to suppress the reaped recombination, efficient charge transfer mechanism, the relation between morphology and catalytic activity etc. Catalytic performance tables are provided for quick assessment of performance of various materials based on testing conditions. Finally, limitations of the present investigations, different challenges associated with the scale-up process of SnS based visible light photocatalyst and future research directions addressing those challenges are discussed. It is concluded that, by considering the ability to absorb visible light, low-cost, non-toxicity, re-usability and chemical stability, SnS nanostructures, composites and heterostructure catalysts can offer a breakthrough in treating real dye contaminated wastewater.