Lead-free organic–inorganic hybrid perovskite heterojunction composites for photocatalytic applications

Abstract

Heterojunction structured MASnI₃/TiO₂ photocatalysts (MA represents CH₃NH₃⁺) are prepared via a facile wet-chemical method and characterized by various techniques. The characterization demonstrates the formation of a heterojunction structure and the good crystallinity of MASnI₃/TiO₂ (1 : 9) (mass ratio of MASnI₃ and TiO₂ is 1 : 9). Moreover, the results also display the improved visible light absorption of MASnI₃/TiO₂ (1 : 9) and low recombination of photoinduced carriers. As a result, MASnI₃/TiO₂ (1 : 9) could completely degrade rhodamine B (97%) in 40 min, which has higher photocatalytic ability than pure MASnI₃ and pure TiO₂. The improved photocatalytic activity could be ascribed to the improved light harvesting ability and easy transfer of photogenerated carriers of the materials generated by the formation of a heterojunction structure and the suitable energy band position between MASnI₃ and TiO₂. In particular, coupling of MASnI₃ and TiO₂ could also avoid oxidation and hydrolysis of MASnI₃ so that the long-term stability of the composite could be efficiently maintained. It is the first report on MASnI₃ and TiO₂ composites being used as photocatalysts for dye degradation. A possible mechanism for the enhancement of photocatalytic activity under light irradiation is also proposed.