Light-driven toluene ammoxidation via mixture photocatalyst of halide perovskite Cs(3)Bi(2)Br(9) and TiO(2).

Benzonitrile is vital for the production of rubbers, pharmaceuticals, and dyes. Traditional benzonitrile synthesis via toluene ammoxidation requires high temperatures (≥350°C), leading to high energy consumption. Here, we demonstrate a photocatalytic route for benzonitrile synthesis under milder conditions (100° to 120°C, 1 to 4 bar, blue light irradiation). Using ammonia, dioxygen, and toluene as precursors, gram-scale benzonitrile (1.751 grams) was produced over a mixture photocatalyst [lead-free halide perovskite cesium bismuth bromide (CsBiBr) + titanium dioxide], demonstrating satisfactory selectivity (85 to 90%) and a linear yield rate of 600 μmol hour. The photocatalyst exhibited excellent quantum efficiencies (up to 40%) and maintained stability over a 30-hour test period. Mechanism studies revealed that, in the presence of an interfacial effect, the perovskite phase primarily activated benzyl carbon (sp)-hydrogen bonds, while titanium dioxide facilitated the oxidation of alcohol intermediate to aldehydes. These benzaldehydes were subsequently converted to benzonitriles via ammoxidation, predominantly catalyzed by CsBiBr through aldimines (RCH═NH).