Electronic Structure Modulation of Nanoporous Cobalt Phosphide by Carbon Doping for Alkaline Hydrogen Evolution Reaction

Abstract Seawater electrolysis under alkaline conditions presents an attractive alternative to traditional freshwater electrolysis for mass sustainable high‐purity hydrogen production. However, the lack of active and robust electrocatalysts severely impedes the industrial application of this technology. Herein, carbon‐doped nanoporous cobalt phosphide (C‐Co 2 P) prepared by electrochemical dealloying is reported as an electrocatalyst for hydrogen evolution reaction (HER). The C‐Co 2 P achieves an overpotential of 30 mV at a current density of 10 mA cm −2 in 1 m KOH, along with impressive catalytic activity and stability at large current densities in artificial alkaline seawater electrolyte containing mixed chlorides of NaCl, MgCl 2 , and CaCl 2 . Experimental analysis and density functional theory calculations reveal that the C atom with strong electronegativity and small atomic radius can tailor the electronic structure of Co 2 P, leading to weakened Co–H bonding toward promoted HER kinetics. Moreover, the C doping introduces a two‐stepped H delivery pathway by forming C–H ad intermediate, thus reducing the energy barrier of water dissociation. This study offers a new vision toward the development of seawater electrolysis for large‐scale hydrogen production.