Unlocking high hydrogen evolution reaction activity with dandelion-inspired nitrogen doped CoP/TiC–C core/branch arrays

Cobalt phosphide for hydrogen evolution reaction (HER) is significantly hindered by the strong binding of hydrogen intermediates on the CoP surface, which does not facilely allow the desorption of H 2 . Here, we introduce a novel strategy to improve the hydrogen evolution catalysis of CoP by modulating the Co–P bond length. This is achieved by incorporating nitrogen into CoP, leveraging the higher electronegativity of nitrogen compared to cobalt and phosphorus. N-doping reduces the electron density around Co atoms, prompting electron redistribution and altering the electronic structure at the Co surface. Consequently, N atoms draw closer to neighboring Co atoms, thereby modifying the Co–P bond lengths. The N-modulated dandelion-like CoP/TiC–C core/branch array exhibits outstanding electrochemical characteristics, achieving an overpotential of only 77 mV at a current density of −10 mA cm −2 in a 1 M KOH solution and maintaining −100 mA cm −2 for over 100 h, demonstrating exceptional durability. X-ray photoelectron spectroscopy, extended X-ray absorption fine structure spectroscopy, and density functional theory studies confirm that the effective manipulation of the Co–P bond length and electronic structure of Co by N doping. This study advances the development of cost-effective transition metal phosphides (TMPs) and provides valuable insights for improving electrocatalytic materials, holding promise for sustainable energy technologies.