Innovative Catalyst Design of Sea-Urchin-like NiCoP Nanoneedle Arrays Supported on N‑Doped Carbon Nanospheres for Enhanced HER Performance

Hydrogen (H₂) stands as a clean energy alternative to fossil fuels, especially within the domain of the hydrogen evolution reaction (HER), offering prospective solutions to mitigate both environmental and energy-related challenges. In this work, we successfully synthesized a sea-urchin-like catalyst, specifically a nickel–cobalt phosphide nanoneedle array on N-doped carbon nanospheres (Ni_0.5Co_1.5P@NCSs), for efficient HER by a sequential hydrothermal and low-temperature phosphating process. The catalyst exhibits sea-urchin-like structures, offering a specific surface area of 298 m² g^–1 and consequently furnishing a greater abundance of active sites. Comparing with non-sea-urchin-like Ni_0.5Co_1.5P@CN catalysts, the Ni_0.5Co_1.5P@NCSs exhibit an overpotential of 163 mV at 10 mA cm^–2, a Tafel slope of 60 mV dec^–1, and a maintained current density of approximately 90% during 50 h of continuous electrolysis. Experiments demonstrate that the outstanding electrochemical properties of the Ni_0.5Co_1.5P@NCSs originate from nitrogen doping of carbon spheres, the distinctive morphology of sea-urchin-like nanoneedle arrays, and simultaneous enhancements in intermediate adsorption energy, charge transfer, and electrolyte diffusion channel shortening. This work emphasizes a preparation strategy for synthesizing an attractive electrocatalyst with a low cost and efficient HER performance.