Engineering g-C₃N₄/CsPbCl₃ Heterojunctions for Selective Photocatalytic Oxidation of Benzylic Alcohols

The selective oxidation of benzylic alcohols to carbonyl compounds is a fundamental transformation in the synthesis of fine chemicals and pharmaceuticals, yet conventional methods often rely on stoichiometric oxidants and generate significant waste. Herein, we report a sustainable heterogeneous photocatalytic system based on engineered g-C₃N₄/CsPbCl₃ heterojunctions for the aerobic oxidation of benzylic alcohols under visible-light irradiation. A series of heterojunction photocatalysts with different compositions was prepared and evaluated, identifying the material containing 10%_W/W CsPbCl₃ as the most efficient catalyst. Under mild conditions and using molecular oxygen as the sole oxidant, a broad range of primary and secondary benzylic alcohols was selectively converted into the corresponding aldehydes and ketones in good to excellent yields. The methodology proved scalable to gram-scale synthesis and the photocatalyst could be readily recovered and reused over multiple cycles while preserving both catalytic activity and structural integrity. Mechanistic studies indicate that substrate activation proceeds through distinct pathways depending on its redox properties, involving either direct single-electron oxidation or oxidation mediated by superoxide radical anion. This work demonstrates the potential of metal halide perovskite/carbon nitride heterojunctions as robust and recyclable photocatalysts for sustainable aerobic oxidation processes and green organic synthesis.