Cesium molybdenum bromide microcrystals for selective photothermal catalytic oxidation of benzyl alcohol

Metal halide perovskites have recently emerged as promising candidates for photothermal catalysis due to their tunable band gaps, high absorption coefficient, and long carrier diffusion length. Most studies have concentrated on 3D perovskite-based heterostructures, while studies on 0D perovskite materials remain largely underexplored, especially in the area of photothermal catalysis. Herein, 0D Cs₂MoBr₆ microcrystals (MCs) with an octahedral morphology are synthesized, demonstrating efficient photothermal activity for the conversion of benzyl alcohol to benzaldehyde with ∼97 % selectivity within 270 min, under normal pressure, at room temperature and without the use of additives or additional oxidants. Mechanistic studies reveal that 0D Cs₂MoBr₆ MCs exhibit ultrafast hot-carrier relaxation (< 1 ps) and strong electron–phonon coupling, which facilitate the generation of thermal energy and enhance reaction activity. Surface potential measurements further demonstrate efficient charge separation in Cs₂MoBr₆, which could facilitate the generation of superoxide radicals. Multiple scavenging experiments confirmed that the photogenerated electrons, holes, ^[rad]O₂⁻, and ¹O₂ play crucial roles in efficient photothermal catalysis. Our work highlights that perovskite can serve as an ideal platform for further exploration of thermocatalysis and photothermal catalysis, opening a new avenue for the use of halide perovskites as photothermal converters.