Porous SnIn4S8 microspheres in a new polymorph that promotes dyes degradation under visible light irradiation

Porous SnIn4S8 microspheres were initially synthesized through a facile solvothermal approach and were investigated as visible-light driven photocatalysts for dyes degradation in polluted water. The photocatalysts were characterized by XRD, SEM, TEM, N2 adsorption–desorption, and UV–vis diffuse reflectance techniques. Results demonstrated that the as-synthesized SnIn4S8 was of a new tetragonal polymorph, showing a band-gap of 2.5 eV, a specific surface area of 197 m2 g−1, and an accessible porous structure as well. The photocatalytic activity of the porous SnIn4S8 was evaluated by decomposition of several typical organic dyes including methyl orange, rhodamine B, and methylene blue in aqueous solution under visible light irradiation. It is demonstrated that porous SnIn4S8 was highly photoactive and stable for dyes degradation, showing photocatalytic activity much higher than binary constituent sulfides like In2S3, SnS2, or even ternary chalcogenide ZnIn2S4 photocatalyst. The excellent photocatalytic performance of porous SnIn4S8 is the consequence of its high surface area, well-defined porous texture, and large amount of hydroxyl radicals.