Adsorption and enhanced photocatalytic activity of the {0 0 0 1} faceted Sm-doped ZnIn2S4 microspheres.

Abstract In this study, the doping effect of samarium on the structure, morphology, adsorption and photocatalytic performance of hexagonal ZnIn 2 S 4 microspheres was studied. The photocatalytic activity of Sm-doped ZnIn 2 S 4 microspheres was evaluated for the photodegradation of Rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. The samples were characterized by XRD, SEM, XPS, UV–vis, TEM, and N 2 adsorption–desorption analysis. The results show that the hexagonal ZnIn 2 S 4 microspheres are composed of nanoplates growing along c -axis with the predominant negative-charged S plane. Compared with the photodegadation of MO dye, the negative-charged {0 0 0 1} facets not only are beneficial for the adsorption of RhB by – N(Et) 2 groups but also can accumulate the separation of photogenerated electrons and holes, enhancing photodegradation efficiency by direct-hole photocatalysis. Moreover, Sm is partially substituted for In in the crystal lattice for forming the doping energy level which promotes the separation of photoinduced electron–hole pairs and enhances absorption of visible light. Hexagonal 2% Sm-doped ZnIn 2 S 4 microspheres with exposed {0 0 0 1} facets resulted in higher photodegradation efficiency of RhB under visible light irradiation.