Magnesium-regulated oxygen vacancies of nickel layered double hydroxides for electrocatalytic water oxidation

Abstract

Generation of doping induced defects in electrocatalysts is becoming an effective strategy for the highly efficient electrocatalytic oxygen evolution reaction (OER). Herein, Mg doped Ni layered double hydroxides (NiMg-LDHs) were prepared by a novel 2-methylimidazole-assisted solvothermal route. Mg-induced generation of oxygen vacancies in the NiMg-LDH host layers during the synthetic process is accountable for the improvement of electron transfer and OH⁻ anion adsorption during electrolysis. Thus NiMg-LDHs exhibit an enhanced performance for the electrocatalytic OER with a low overpotential (η₁₀: 254 mV) at a current density of 10 mA cm⁻² and high mass activity (56.3 A g⁻¹) at an overpotential of 321 mV. The electrocatalytic activity was further improved after introducing reduced graphene oxide (rGO) to form hybrid composites of NiMg-LDHs/Go with decreasing of η₁₀ to 232 mV. This finding highlights the promise of s-block metals in regulating electrocatalytic activity for the OER, which is helpful for extending the scope of superior electrocatalysts in energy-related fields.