A CsPbBr₃ /TiO₂ Composite for Visible-Light-Driven Photocatalytic Benzyl Alcohol Oxidation

Halide perovskites have attracted great attention in the fields of photovoltaics, LEDs, lasers, and most recently photocatalysis, owing to their unique optoelectronic properties. The all-inorganic halide perovskite CsPbBr₃ /TiO₂ composite material catalyzes selective benzyl alcohol oxidation to benzaldehyde under visible-light illumination. The catalyst, which is prepared by a facile wet-impregnation method, shows very good selectivity towards benzaldehyde (>99 % at 50 % conversion). Action spectra and electron spin resonance (ESR) studies reveal that photoexcited electrons formed within CsPbBr₃ upon visible-light illumination take part in the reaction via reduction of oxygen to form superoxide radicals. The detailed post-catalysis characterization by UV/Vis and X-ray photoelectron spectroscopy, X-ray diffraction, and high-angle annular dark-field scanning transmission electron microscopy studies further demonstrated the good stability of CsPbBr₃ in terms of morphology and crystal structure under the reaction conditions. This study sheds light on promising new photocatalytic applications of halide perovskites.