Unleashing the charge compensation effect for enhanced electrochemical water-splitting using low-valent magnesium-inserted CoP

Abstract

Cobalt phosphide (CoP) is a promising electrocatalyst due to its abundance and excellent stability in alkaline solution. However, its poor conductivity and intrinsic catalytic activity limit its potential in electrochemical water splitting. To address this, a heterogeneous atom doping strategy has been proposed to synthesize magnesium-doped cobalt phosphide nanoneedle arrays, or Mg-doped CoP. Our theoretical calculations show that transition metal Mg atoms doping into the CoP lattice can enhance the electronic structure and modulate the free energy of reacting species, resulting in a significant improvement in the intrinsic catalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) process. The electrochemical tests reveal that the optimal 10% Mg-doped CoP nanoneedle arrays exhibit outstanding HER and OER electrocatalytic activities with overpotential values of 85 and 236 mV at 10 mA/cm2, respectively, outperforming previously reported CoP-based catalysts. This study not only presents a strategy to enhance the catalytic activity of CoP-based materials, but also offers a reference for achieving efficient electrochemical hydrogen production by hydrolysis.