Ru-doping modulated cobalt phosphide nanoarrays as efficient electrocatalyst for hydrogen evolution rection

Electrochemical water splitting is regarded as a prospective means for H2 production. The lack of efficient active sites and the sluggish kinetics in alkaline media remain the major obstacles for hydrogen evolution reaction (HER). Herein, a rational construction of Ru-doped cobalt phosphide leaf-like nanoarrays supported on carbon cloth (Ru-CoP NAs) was designed via a MOF-derived route and subsequent phosphating treatment for accelerating HER in the alkaline. The unique hierarchical structure is conductive to exposing more active sites and accelerating the diffusion of electrolyte and the release of H2 bubble. The optimized Ru-CoP-2.5 NAs exhibits a small overpotential of 52 mV to drive 10 mA cm-2 for HER and a low Tafel slope of 39.7 mV dec-1 in 1 M KOH, which outperforms most of other reported CoP-based electrocatalysts. Furthermore, density functional theory (DFT) calculations unveil that Ru dopants can modulate the electron environment around pure CoP and optimize the adsorption energy of H*, accelerating the reaction kinetics. This work provides an insight to promote the electrocatalytic activity of metal phosphide for hydrogen production.