Engineering Mn-doped Co-based heterostructures with oxygen vacancies toward efficient industrial-scale water...

Developing efficient and durable catalysts for the oxygen evolution reaction (OER) is essential for advancing water-splitting technologies. In this study, we present a self-supported Mn_0.10Co_0.90-CoCo₂O₄/NF catalyst featuring a 2D/2D heterostructure, consisting of nanowire arrays coated with ultrathin nanosheets. This unique architecture forms interconnected 3D porous channels, enhancing electrolyte penetration, oxygen diffusion, and mass transport. X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and zeta potential (ζ) measurements reveal that Mn doping facilitates surface reconstruction and increases oxygen vacancies, optimizing the electronic structure and boosting catalytic activity. In situ Raman spectroscopy confirms that CoOOH is the active center, while operando electrochemical impedance spectroscopy demonstrates that strong electronic interactions at the heterogeneous interface enhance charge transfer. The Mn_0.10Co_0.90-CoCo₂O₄/NF catalyst exhibits good electrocatalytic performance, achieving low overpotentials (178/233 mV at 10/50 mA cm^-2) and exceptional stability (50 mA cm^-2 for 280 h) in alkaline electrolytes. This study underscores the synergistic effects of oxygen vacancy engineering, Mn-Co interactions, and a hierarchical structure in improving conductivity, active site accessibility, and reaction kinetics. Mn_0.10Co_0.90-CoCo₂O₄/NF emerges as a promising, cost-effective alternative to noble metal catalysts for industrial-scale water electrolysis applications.