Quasi-1D Mn2O3 nanostructures functionalized with first-row transition-metal oxides as oxygen evolution catalysts

The development of cheap and efficient catalysts for the oxygen evolution reaction (OER) plays a critical role for sustainable energy conversion and storage. Herein, we report on Mn2O3-based systems supported on nickel foams and functionalized with first-row transition-metal (Fe, Co, Ni) oxide nanoparticles (NPs) as OER electrocatalysts in alkaline media, fabricated by a plasma-assisted process. The remarkable substrate porosity and high Mn2O3 active area, due to the quasi-one-dimensional nano-organization, enabled an efficient ultradispersion of Fe2O3, Co3O4, and NiO NPs into Mn2O3 and an intimate oxide-oxide interfacial contact, enhancing thus charge carrier transport and facilitating reactants and products diffusion. Among the developed systems, Fe2O3-Mn2O3 yielded the highest electrocatalytic activity, corresponding to a low overpotential of ~350 mV at 10 mA × cm-2 and a Tafel slope of 70 mV × dec-1, allowing high current density values. The obtained performances, discussed in relation to the material properties, are superior to almost all the state-of-the-art manganese oxide catalysts and compare favorably with various noble-metal-based systems, paving the way to additional activity improvements via compositional and interfacial engineering.