Rapid Acidic Media Growth of Cs₃Bi₂Br₉ Halide Perovskite Platelets for Photocatalytic Toluene Oxidation

Organic ligands with long carbon chains have been widely utilized to mediate the growth of halide perovskite crystals with tunable morphologies. However, the presence of these surfactants on the surface of halide perovskites limits their performance in photocatalytic conversion applications. Herein, a rapid synthetic protocol to prepare Cs₃Bi₂Br₉ platelets with clean surfaces and controllable thickness in a dilute H₂SO₄ solution after a quick cooling process in liquid nitrogen or mixtures of dry ice is reported. Electron microscopy and X‐ray diffraction reveal the preferential exposure of (00l) facets in Cs₃Bi₂Br₉ platelets with variable thickness from 100 to 500 nm. Infrared spectroscopy hints that the selective chemisorption of ethyl acetoacetate on (00l) facets of bismuth perovskites regulates the growth of the crystals. These novel lead‐free halide perovskite platelets can drive the photo‐oxidation of toluene to benzaldehyde with high selectivity (≥88%) and stability over 36 h.