Enhancing hydrogen oxidation electrocatalysis of nickel-based catalyst by simultaneous chemical anchoring and electronic structure regulation

Designing electrocatalysts for hydrogen oxidation reaction (HOR) in alkaline media is crucial but challenging. Among all available electrocatalysts, Ni-based materials are recognized as the most potential precious-metal-free electrocatalysts for HOR. However, they still suffer from serious problems including low activity and poor stability. In this work, a synergistic chemical anchoring and electronic structure regulation strategy is proposed to gain both high electrocatalytic activity and stability for Ni-based HOR catalyst. N-doped graphite nanoflakes (N-GFs) support with abundant N anchoring sites can stabilize the loading of Ni-based active species, giving rise to an excellent stability of the catalyst. Meanwhile, the rationally designed heterostructure in the active Ni3N/Ni can trigger the electron transfer across the heterointerface, which optimizes the binding energy of the reaction intermediates, resulting in an accelerated the Volmer reaction. Benefited from the rational design, Ni3N/Ni/N-GFs exhibits excellent mass activity (42.7 A gNi-1 at the overpotential of 50 mV) and stability (more than 24 h continuous operation). Moreover, the Ni3N/Ni heterostructure performs better in HOR electrocatalysis than individual Ni or Ni3N. These experimental results are rationalized by the theoretical simulations, which demonstrate that the heterostructure effectively weakens the hydrogen adsorption, optimizes the hydroxyl adsorption, and decreases the water formation reaction barrier.