Efficient Synthesis and Enhanced Electrochemical Performance of MnCoO Catalysts for Oxygen Evolution Reaction

The development of oxygen evolution reaction (OER) catalysts with high activity, long-term stability, and cost-effectiveness is crucial in large-scale hydrogen production. In this study, we present a simple and efficient synthesis strategy for MnCoO catalysts using a two-step co-precipitation and annealing method. MnCoO-1 and MnCoO-2 were synthesized with different Mn:Co precursor ratios (1:3 and 2:2, respectively), resulting in enhanced electrocatalytic activity for OER in an alkaline electrolyte. MnCoO-1 exhibited hexagonal plate morphology, while MnCoO-2 showed cubic nanostructures with a small number of nano-plates. Compared to Co 3 O 4 and MnCoO-2, MnCoO-1 demonstrates a significantly lower overpotential, achieving an OER current density of 75 mA cm −2 at 546.0 mV, indicating enhanced OER activity. Moreover, MnCoO-1 achieves an even higher OER current density of 100 mA cm −2 at an overpotential of 606 mV versus RHE, which is considerably lower than the overpotentials observed for Co 3 O 4 (733.7 mV) and MnCoO-2 (776.0 mV) catalysts. This improvement can be attributed to the unique morphology and structure of MnCoO-1, where Mn ions were efficiently incorporated into the Co 3 O 4 lattice without disrupting its crystal structure. Furthermore, MnCoO-1 demonstrated remarkable long-term electrochemical stability against OER in a 1.0 M KOH aqueous electrolyte, maintaining a high current density of 50 mA cm −2 in 24 h. Graphical Abstract