Paired Electrochemical N–N Coupling Employing a Surface-Hydroxylated Ni3Fe-MOF-OH Bifunctional Electrocatalyst with Enhanced Adsorption of Nitroarenes and Anilines

Paired electrolysis employing both anodic and cathodic half reactions for the synthesis of value-added chemicals is an ultimate energy-efficient approach. Here, we show that paired reductive coupling of nitroaromatics into azoxy-aromatics and oxidative coupling of aromatic amines into azo-aromatics can be realized with high efficiency and selectivity employing the surface-hydroxylated Ni₃Fe metal-organic framework (Ni₃Fe-MOF-OH) bifunctional electrocatalyst. The competitive hydrogen and oxygen evolution reactions are suppressed due to the adsorption of nitroarenes and anilines via surface hydroxyls of the electrocatalyst. Simultaneous cathodic and anodic N-N coupling of a wide range of nitroaromatics and aniline derivatives are realized with high conversion and selectivity at an overall bias of 1.4 V in an undivided cell in 1 M KOH electrolyte. Ni₃Fe-MOF-OH displays a high stability and enables gram-scale synthesis of azo- and azoxy-aromatics with a satisfactory yield and Faraday efficiency, offering an efficient synthetic protocol for applications.