Manganese‐Cobalt Oxides on Carbon Paper Self‐Supported Electrodes With Bimetallic Synergy and Oxygen Vacancies for Highly Efficient Water Oxidation

The development of efficient and durable non‐noble metal electrocatalysts for the acidic oxygen evolution reaction (OER) remains a critical challenge due to the sluggish four‐electron kinetics and the reliance on scarce iridium/ruthenium‐based materials. Herein, we report a facile one‐step calcination method to fabricate self‐supported manganese‐cobalt oxide electrodes on carbon paper (MnCoO _x /CP) with tailored oxygen vacancies (O _v ) and electronic structures. By systematically optimizing the calcination temperature, holding time, and Mn/Co ratio, we achieve synergistic regulation of morphology, defect concentration, and catalytic activity. The optimal MnCoO _x /CP electrode delivers competitive acidic OER performance, with low overpotentials of 310.6 and 377.6 mV at 10 and 50 mA cm ⁻² in 0.5 M H ₂ SO ₄ , respectively. Moreover, it exhibits excellent long‐term stability with only a 1.6% potential increase after 25 h at 50 mA cm ⁻² , and superior dual‐pH adaptability (136.5 mV at 10 mA cm ⁻² in alkaline medium). The enhanced performance is attributed to strong Mn–Co electronic interaction, abundant oxygen vacancies, and mixed‐valence states, which remarkably accelerate charge transfer and optimize the adsorption energy of OER intermediates. This work provides a truly low‐cost, scalable strategy for designing high‐performance nonnoble metal oxide electrocatalysts for wide‐pH water splitting.