Cerium-doped nickel phosphide (Ni2P): Highly efficient electrocatalyst for hydrogen evolution reaction

Abstract

Here, cerium-doped nickel phosphide is introduced as a novel electrocatalyst for HER. Nickel phosphide doped with different cerium contents was synthesized by a two-step vapor-solid reaction method. The electrocatalysts were characterized by various physical and electrochemical analyses. The physical characterization results indicated that cerium doping decreased the crystallite size and subsequently the average particle size of pure Ni2P. Also, electrochemical measurements showed that cerium doping generally bettered the performance of pure Ni2P in HER by improving its electrochemical characteristics e.g. electrochemical hydrogen adsorption, energy efficiency, number of active sites, intrinsic activity, and charge transfer behavior. The effects of cerium doping were also examined theoretically using density functional theory (DFT) calculations, which provided an in-depth understanding of cerium doping. The optimum amount of cerium dopant was found at 3 %mol where Ce0.03Ni2P with the onset potential of 73.3 mV, and an overpotential of 150.0 mV at a current density of 10 mAcm2, and Tafel slope of 76.7 mVdec. in 1.0 M KOH showed the highest activity. Such a high activity, along with stable and durable performance, introduces Ce0.03Ni2P as an efficient electrocatalyst for HER.