Ultraeven Mo-Doped CoP Nanocrystals as Bifunctional\nElectrocatalyst for Efficient Overall Water Splitting

Abstract

To\ndevelop precious-metal-free bifunctional catalysts for overall\nwater splitting, ultraeven Mo-doped CoP composites (Mo-CoP) have been\nfabricated by an in situ phosphorization protocol using CoMo-layered\ndouble hydroxide (CoMo-LDH) as the precursor. The ordered arrangement\nof cations in the CoMo-LDH could be easily phosphored and generate\nthe ultraevenly dispersed Mo element within the CoP structure, resulting\nin the excellent bifunctional catalyst for overall water splitting.\nThe hydrogen evolution reaction (HER) and oxygen evolution reaction\n(OER) catalytic activities of the composites present an increase first\nand then a decreasing tendency with increased Mo doping content. Among\nall the Mo-doped CoP materials, the composite with a Mo/Co mole ratio\nof 1/2.3 presents the highest HER activity and stability in acidic\nconditions. At the current density of −10 mA·cm^–2 in 0.5 M H₂SO₄, the overpotential is only\n116 mV. In addition, the composite also presents excellent HER and\nOER performance under alkaline conditions. The overpotential is 118\nmV for HER and 317 mV for OER at 10 mA cm^–2 in 1\nM KOH. It requires a cell voltage of 1.7 V to achieve a current density\nof 10 mA·cm^–2 and maintains a stable water-splitting\ncurrent for at least 24 h, which is superior to most reported alkaline\nmedia. This simple and efficient synthetic approach could also be\nused for ultraeven doping between other transition metal ions.