Nickel Nanoparticles Confined in Core-Shell Derived from Covalent Organic Framework for the Efficient Electrocatalytic NO Reduction to NH₃

The electrocatalytic nitric oxide reduction reaction (NORR) has attracted significant attention as an ecofriendly alternative to the conventional Haber-Bosch process for producing ammonia (NH3). However, the poor selectivity to NH3 and low catalyst stability under harsh conditions are great challenges in NORR. Herein, the core-shell structure of nickel nanoparticles enclosed with a nitrogen-doped carbon layer (Ni@NC) electrocatalyst derived from covalent organic frameworks is employed for high performance in NORR. The Ni@NC-700 achieved the highest FENH3 of 82.94% with an NH3 yield rate of 19.00 mu mol cm(-2) h(-1) at 0.16 V (vs reversible hydrogen electrode) in a 0.1 M HClO4 electrolyte. Control experiments revealed that nickel nanoparticles (Ni NPs) acted as active centers in Ni@NC for efficient production of NH3. The ideal carbon shell protection of Ni NPs and the high inherent catalytic TOF of Ni@NC-700 revealed a promising candidate for an efficient NORR electrocatalyst. The stability test demonstrated the remarkable stability of Ni@NC. The Ni NPs were protected by carbon nanostructures resembling core-shell catalysts, preventing metal dissolution during rough electrolysis.