Ligand-Mediated Tailoring of Self-Supported MnxOy@Ni(OH)2 Nanoheterostructures with Enhanced OER Performance

We report a colloidal synthesis strategy for producing MnxOy@Ni(OH)2nanoheterostructures under mild conditions, i.e., low temperature and ambient pressure. The role of carboxylic acid ligands in directing the synthesis is systematically explored, revealing that lower ligand concentrations along with low-molecular weight molecules favor the formation of well-defined MnxOy@Ni(OH)2heterostructures. Electrochemical characterization demonstrates that the resulting nanocomposites exhibit significantly enhanced electrochemical surface area and oxygen evolution reaction (OER) activity compared to their single-component counterparts. Specifically, MnxOy@Ni(OH)2achieves a low overpotential of 299 mV at 10 mA cm–2, a Tafel slope of 61 mV dec–1, and a low charge transfer resistance of 9 Ω. The improved OER performance is attributed to the synergistic effect between the Ni(OH)2nanosheets, which facilitate *OOH intermediate formation, and the MnO2component, known for its intrinsic catalytic activity. Additionally, Mn3O4serves as a stabilizing phase and precursor to MnO2, contributing to the overall durability and structural integrity of the catalyst.