Regulating the tip effect on urchin-like N-NiCoP/NF as high-performance electrocatalyst for hydrogen evolution reaction

Transition metal phosphides (TMPs) have emerged as highly promising electrocatalysts for the hydrogen evolution reaction (HER) due to their earth-abundance reserves, rich electrochemical active sites and high stability. Herein, to cope with the inert atoms on the basal plane and sluggish electrochemical kinetics, we propose a novel strategy involving the in-situ conversion of urchin-like NiCo-LDH into a nitrogen-doped NiCoP electrocatalyst on nickel foam (N-NiCoP/NF) via a hydrothermal-phosphorylation approach. In this structure, NiCoP nanoneedles are assembled into a tip-rich urchin-like structure on NF substrates, delivering abundant mismatched active sites for capturing catalytic intermediates, accelerating charge transport and constructing an optimized heterogeneous interface. Additionally, heterogeneous N-atom doping can further regulate the charge distribution of NiCoP needles, and significantly contribute to enhancing the electrocatalytic performance for HER. Benefitting from the synergistic effect of the abundant active sites provided by tip-rich NiCoP nano-urchin, electronic modulation by heterogeneous N-species and optimized interfacial coupling, the N-NiCoP/NF electrocatalyst displays low overpotentials of 75 mV and obtains 10 mA cm-2 in alkaline electrolyte without significant decrease even after 5000 cycles, indicating high catalytic activity and stability. This study provides a low-cost and controlled approach for developing novel heteroatom-doped TMPs for HER applications.The various properties of the materials surprisingly demonstrate that our diatomic codoping strategy prepared by facile hydrothermal phosphatization with annealing can effectively enhance the HER properties of the materials. The unique morphology possessed by the material provides advantages such as active sites and accelerated charge transport that can further enhance the catalytic performance of the material, which is further formalized by our DFT calculations. Our theoretical and experimental studies provide a good case for the development of simple and low-cost electrocatalytic materials.