Outstanding cooperation of all-inorganic CsPbI 3 perovskite with TiO 2 forming composites and heterostructures for photodegradation

Semiconductor materials have a great potential to be used as a photocatalyst in several applications from dye degradation and water treatment up to solar cells. All-inorganic halide perovskite CsPbI 3 and TiO 2 with anatase structure were synthesized, studied, and compared as single samples and also forming heterostructures and composites. Structural, morphological, and optical characterizations reveal the successful synthesis of CsPbI 3 and TiO 2 compounds and the formation of both composites and heterostructures CsPbI 3 /TiO 2 . Methylene blue organic dye was used as a model for the study and evaluation of the photocatalytic activity exhibited by the produced semiconducting samples. The photocatalytic activity for MB degradation in methanol was investigated separately for TiO 2 and CsPbI 3 and their formation as composites and heterostructures. We have observed that when CsPbI 3 perovskite is combined with TiO 2 , a cooperative mechanism involving the formation of intermediate phases promotes photobleaching with a kinetic constant rate much higher than both compounds separated or forming heterostructures. The CsPbI 3 /TiO 2 causes MB mineralization by an oxygen-dependent mechanism. On the other hand, very high constant rate of the MB photodegradation can be observed by CsPbI 3 perovskite even in a solution without the presence of dissolved oxygen. The presence of structural defects interstitials, vacancies , and under-coordinated Pb 2+ ions on the surface of the perovskite particles may be formed during light irradiation and act as catalytic centers. The kinetic constant rate and the mechanism of MB photobleaching and the occurrence of dye mineralization can be tuned in feasible by simple strategies involving the formation of heterostructure and composites. Graphical abstract