Efficient CoNi-bimetal phosphide embedded carbon matrix derived from a novel phosphonate complex for hydrazine-assisted electrolytic hydrogen production

Abstract

Electrochemical water splitting is considered as a sustainable and clean technology for hydrogen production, but is still limited by the sluggish kinetics of anodic oxygen evolution reaction (OER). Hydrazine oxidation reaction (HzOR) requires much lower thermodynamic oxidation potential and produces zero-carbon molecules, thus becoming a promising alternative to replace OER for realizing energy-saving hydrogen production. Herein, a CoNi-bimetal phosphide nanoparticles embedded P doped carbon matrix structure ((Co0.6Ni0.4)2P@PC) is constructed via annealing a novel precursor composed of CoNi-bimetal sites and P contained ligands for hydrazine-assisted water splitting. The P element can simultaneously in situ phosphorize the metal sites and carbon atoms. The (Co0.6Ni0.4)2P@PC exhibits outstanding hydrogen evolution reaction (HER) performance with an overpotential of 67.9 mV at 10 mA cm−2 and requires an ultralow potential of -83 mV at 10 mA cm−2 for HzOR in alkaline electrolyte. Furthermore, the electrolyzer assembled with the (Co0.6Ni0.4)2P@PC as both cathode and anode delivers a cell voltage of merely 0.048 V which is much lower compared with the OER-HER system (1.60 V) for reaching 10 mA cm−2. The present work develops an eco-friendly synthetic method for designing low-cost and highly efficient carbon matrix incorporated phosphide electrocatalyst for energy-saving hydrogen production.