ABSTRACT Conventional synthesis of aromatic azo compounds through oxidative coupling of aniline typically relies on hydrogen peroxide or pressurized oxygen environments. In this study, a defective UiO‐66 catalyst (def‐UiO‐66) with a high density of structural defects was synthesized via an unconventional solvothermal approach. Under an ambient oxygen atmosphere, the def‐UiO‐66 catalyst exhibits exceptional activity in the oxidative coupling of aniline in water, affording 97% aniline conversion with 93% selectivity toward azobenzene (AB). The def‐UiO‐66 also demonstrates outstanding cyclic stability over ten consecutive tests along with broad substrate versality. Experimental evidence and density functional theory (DFT) calculations demonstrate that the abundant defects, i.e., unsaturated zirconium sites in the def‐UiO‐66 effectively facilitate aniline adsorption and activate N‐H bonds, with reactive oxygen species (including O 2 − and 1 O 2 ) playing critical roles in the oxidative coupling process. These results provide a mechanistic basis for the preferential formation of AB. This work offers valuable insights for designing efficient, sustainable, and recyclable catalytic systems for aniline oxidative coupling reactions.
Li et al. (2026) studied this question.