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

Aromatic azo compounds are widely used in pharmaceutical and in-dustrial regions, but their commercial synthesis still encounters chal-lenges of low selectivity and environmentally unfriendly conditions. Here, we report a photoelectrocatalytic (PEC) strategy for azoben-zene 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 supe-rior performance of BiVO4-NA is attributed to the moderate adsorp-tion strength of aniline and suitable valence band position for selec-tive aniline oxidation. BiVO4-NA exhibits a broad scope for various aromatic azo compounds with high selectivity. Furthermore, we de-signed 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 co-balt phosphide (CoP), showing maximum electron economy for value-added chemicals productions.

Automated summary

In this study, a photoelectrocatalytic strategy for the synthesis of azobenzene from aniline using porous nanoarrays of bismuth vanadate as a photoanode was reported. The reaction exhibited >99% selectivity and 87.4% Faradaic efficiency under illumination. The superior performance of bismuth vanadate nanoarrays was attributed to the moderate adsorption strength of aniline and suitable valence band position for selective aniline oxidation.