Hydrogen-Ion-Mediated Ni/Ni(OH)2 Dual Sites to Synergistically Accelerate *OH/Organics Adsorption for Highly Efficient Electrochemical 5-Amino-1 H -tetrazole Electrooxidation within a Wide Potential Rang

Abstract

Nitrogen-rich azo-tetrazole compounds are essential structural scaffolds for energetic materials, dyes, and agrochemicals, owing to their favorable energetic and physicochemical properties. Potassium 5,5′-azotetrazolate (PZT), as a representative and efficient nitrogen-rich azo-tetrazole material, is conventionally synthesized via thermochemical oxidative coupling, which suffers from safety hazards and environmental pollution. Electrochemical synthesis offers a compelling alternative, but the severe competitive oxygen evolution reaction (OER) impedes achieving highly-efficient N–N coupling activity and Faradaic efficiency (FE). Herein, a core–shell CF@CuO@Ni/Ni(OH)2 electrode is fabricated through controlled H+-mediated electrodeposition. The CF@CuO core provides a three-dimensional (3D) conductive scaffold and suppresses the competing OER, while the Ni0/Ni(OH)2 shell undergoes electrochemical reconstruction into coexisting NiO/NiOOH working phases. The catalyst reaches 10 mA·cm–2 at 1.16 V vs RHE and maintains a Faradaic efficiency above 94% over a broad potential range of 1.2–1.6 V. Combined electrochemical, spectroscopic, kinetic, and computational analyses prove that surface-adsorbed *OH initiates 5-AT dehydrogenative coupling via a PCET pathway on the reconstructed NiO/NiOOH surface. NiO triggers synergistic *OH/5-AT adsorption, while NiOOH facilitates dehydrogenation. In a continuous-flow AEM electrolyzer, the system operates at 500 mA cm–2 over 300 h while sustaining PZT production (purity ≥99%) and H2 evolution. Extension to DAT and DAF further demonstrates the transferability of the catalyst toward related amino-functionalized N-heterocycles undergoing oxidative N–N coupling. This work establishes that reconstructed NiO/NiOOH dual sites, supported on an OER-suppressing CuO scaffold, enable selective and energy-efficient N–N oxidative coupling of amino heterocycles.