Photoelectrocatalytic synthesis of aromatic azo compounds over porous nanoarrays of bismuth vanadate

Aromatic azo compounds are widely used in pharmaceutical and industrial regions, but their commercial synthesis still encounters challenges of low selectivity and environmentally unfriendly conditions. Here, we report a photoelectrocatalytic (PEC) strategy for azobenzene synthesis from aniline over porous nanoarrays of bismuth vanadate (BiVO4-NA) as a photoanode coupled with H2 production, achieving >99% selectivity, 87.4% Faradaic efficiency, and 100 h stability under illumination. Experimental data demonstrate that the reaction follows an oxidative coupling mechanism, and the superior performance of BiVO4-NA is attributed to the moderate adsorption strength of aniline and suitable valence band position for selective aniline oxidation. BiVO4-NA exhibits a broad scope for various aromatic azo compounds with high selectivity. Furthermore, we designed a PEC system that co-produces azo compounds via N–N coupling reactions at bipolar by combining the oxidative coupling of aniline with nitrobenzene reductive coupling at cathode over cobalt phosphide (CoP), showing maximum electron economy for value-added chemicals productions.