Highly stable halide perovskites for photocatalysis via multi-dimensional structure design and in situ phase transition.

Lead halide perovskite CsPbBr 3 quantum dots (QDs) possess several desirable features which enable them to be promising candidates for photocatalysis. However, the instability caused by their inherent liquid-like ionic properties hampers their further development. Herein, this work employs the surficial molecular modification strategy and a multi-dimensional structure design to ease the instability issue. The additive 2-phenylethanamine bromide (PEABr) can serve as a ligand to compensate for stripping the amine ligands and passivate the surficial bromide vacancy defects of CsPbBr 3 QDs in photocatalysis. In addition, PEABr acts as a reactant to form 2D and quasi-2D perovskite nanosheets. The addition of a small amount of these nanosheets into QDs can enhance their general stability due to their unique layered structures. Moreover, PEABr can trigger the phase transition of cubic CsPbBr 3 into tetragonal CsPb 2 Br 5 . The newly formed Z-scheme homologous heterojunctions further improve the catalytic performance. Simulated photocatalytic dynamics reveals that our multi-dimensional structure favors decreasing the reaction barrier energy and then facilitating the photocatalytic reaction. Therefore, the electron consumption rate of our multi-dimensional perovskites doubles that of pristine CsPbBr 3 QDs and also has superior long-term stability.