Halide Perovskite Nanocrystals for Shaping Pt Nanostructures

Halide contents in the reaction system during the formation of lead halide perovskite nanocrystals remained a critical parameter for controlling their surface facets and optical properties. In addition, herein, the impact of halide ions has also been explored as a deciding factor for the formation of metal(0)-perovskite nanocrystal heterostructures. Using CsPbBr3 and Pt, it is observed that minimum bromide concentration is ideal for epitaxial connection of Pt particles, but with a greater amount, these are disconnected during annealing. In addition, CsPbBr3 perovskite nanocrystals also acted here as the catalyst for nucleating and shaping Pt particles, which on altering reaction parameters tuned their shape from small dots to cubes and also in rod shape. The control of obtaining one-to-one or one-to-many types of heterostructures, as well as excess Pt particles retained in bulk solution, are also established. Formation of all these shapes is further observed related to the host nanocrystals, as without CsPbBr3 no such structures of Pt are seen in control reactions. This catalytic nucleation and formation of Pt particles on the surface of CsPbBr3 and their retention or ejection from the surface of CsPbBr3 are correlated with the halide contents and the extent of epitaxial growth between these two materials. Hence, rather than using the traditional approach, herein, CsBr to CsPbBr3 transformation protocol is used for the formation of required excess halides in the reaction system, and phenacyl bromide is used for bringing and tuning shapes of the perovskite nanocrystals. Details of all these studies are investigated and the shaping of Pt particles are correlated to the facets, sizes, and shapes of CsPbBr3 perovskite nanocrystals.