Boosting hydrogen evolution via optimized hydrogen adsorption at the interface of CoP3 and Ni2P

Abstract

Transition metal phosphides (TMPs) have emerged as highly active catalysts for the hydrogen evolution reaction (HER). Herein, we report a novel excellent CoP₃/Ni₂P catalyst for the HER with a small onset potential of 51 mV vs. RHE, a low Tafel slope of 49 mV dec⁻¹, a small over-potential value of 115 mV at 10 mA cm⁻², and outstanding long-term stability. The normalized polarization curve also shows that CoP₃/Ni₂P has the best intrinsic catalytic activity compared to pure CoP₃ and pure Ni₂P. Density functional theory (DFT) calculations reveal that the remarkably enhanced catalytic activity is due to the interface effect of CoP₃/Ni₂P. The strong interactions at the interface can optimize the electronic environment around the active sites, leading to suitable H⁺ adsorption and H₂ formation kinetics and energetics, thereby enhancing the catalytic activity.