Photocatalytic Synthesis of Aromatic Nitriles Using TiO ₂ Nanotubes Decorated With Bismuth Halide Perovskite Nanodots

The aromatic nitrile synthesis via ammoxidation of methylarenes typically requires harsh reaction conditions (≥ 350°C or ≥ 15 bar O 2 ). Here, TiO 2 nanotubes (NTs) homogeneously decorated with halide perovskite Cs 3 Bi 2 Br 9 (CBB) nanodots (< 2 nm) were established as efficient photocatalysts for the sustainable synthesis of aromatic nitriles. A yield rate up to 353 µmol g −1 h −1 was achieved under mild conditions (100°C–120°C, 1–4 bar, and blue light irradiation) with decent nitrile selectivity (85%–88%). Enhanced photo‐induced charge diffusion and structural stability of CBB nanodots afforded excellent quantum efficiencies (up to 26.7%) and sustained photocatalytic activity in long‐term ammoxidation (45 h). Additionally, 11 methylarenes were successfully converted to the corresponding nitriles over the CBB/TiO 2 NT photocatalyst. Mechanism investigations revealed a synergistic catalytic effect between perovskite nanodots and TiO 2 NTs. CBB nanodots activated benzylic C(sp 3 )–H bonds and promoted the oxidation of aldimine intermediates, while TiO 2 NTs with unique adsorption of alcohol intermediates accelerated their partial oxidation to aldehydes.