Facile Synthesis of 3d Transition-Metal-Doped α-Co(OH)₂ Nanomaterials in Water-Methanol Mediated with Ammonia for Oxygen Evolution Reaction

Layered cobalt hydroxides are cost-efficient electrocatalysts for oxygen evolution reaction (OER) in the field of energy conversion. Herein, we developed a facile synthesis method of 3d transition-metal-doped α-Co(OH)₂ nanomaterials mediated with ammonia in water-methanol at room temperature. The doping of Cu²⁺ and Ni²⁺ leads to flower-like nanostructures similar to pure α-Co(OH)₂, whereas the doping of Fe²⁺ produces nanoparticles with more than 2 times larger surface area in comparison with the Cu²⁺- and Ni²⁺-doped nanoflowers. The obtained dispersion with the addition of Nafion can be used directly as an electrocatalyst for OER with excellent catalytic activity, especially that the overpotential of Fe²⁺ doped is as low as 290 mV at 10 mA cm^-2 and the turnover frequency is improved by 3 times as compared with that of α-Co(OH)₂. Furthermore, the catalyst can be loaded onto foam nickel, which presents excellent durability with the current density unchanged under continuous chronoamperometry reaction for as long as 12 h and almost quantitative faradaic efficiency. The superior electrocatalytic properties combined with the simple synthesis without the tedious purification procedure is very promising for OER.