The direct synthesis of nitroaromatics from waste nitrogen sources represents a longstanding challenge in organic electrosynthesis, as prevailing heterogeneous C─N coupling pathways are kinetically and thermodynamically constrained to producing reduced nitrogen species. Herein, we report a photoelectrocatalytic strategy that bypasses these limitations by leveraging in situ-generated nitrogen dioxide radicals (·NO2) as homogeneous nitrating agents. Using a BiVO4 photoanode and nitrite as a sustainable nitrogen feedstock, ·NO2 radicals mediate the direct C─H nitration of benzene via a radical aromatic substitution mechanism, obviating the need for reactant co-adsorption. By engineering a polar interfacial layer on the photoanode, the local concentration of nitrite was remarkably enhanced, thereby boosting ·NO2 generation and enabling efficient coupling even under practically relevant dilute conditions (5 mM NO2 -). The optimized photoanode achieves a 29.6-fold enhancement in p-dinitrobenzene production rate over the unmodified BiVO4 and the scaled system further demonstrated a p-DNB production rate of ∼58 µmol·h-1 with near exclusive selectivity and exceptional operational stability. This work establishes a waste valorization and sustainable platform for the synthesis of nitroaromatics from ambient conditions.
Dong et al. (Tue,) studied this question.