MnZnFe₂O₄@SrWO₄ Ceramic Composite as an Efficient Non-Noble Electrocatalyst for the Oxygen Evolution Reaction in Alkaline Media

The development of efficient, earth abundant electrocatalysts for the oxygen evolution reaction (OER) is essential for alkaline water electrolysis. In this work, we prepared MnZnFe₂O₄, SrWO₄, and a MnZnFe₂O₄@SrWO₄ ferrite–tungstate heterostructure by simple co-precipitation and hydrothermal routes and evaluated them as OER catalysts in 1 M KOH. The catalysts are characterized by XRD, UV–Vis, FTIR, SEM, and EDX. The catalysts exhibit phase-pure components with intimate contact between the two phases, and a smaller particle size for the composite. The MnZnFe₂O₄@SrWO₄ exhibits modified electronic structure possibly due to the electronic interaction between Fe and W centers. Electrochemical measurements demonstrated an overpotential of 200 mV at 10 mA cm^-2, that exhibits a reduced Tafel slope (150 mV dec⁻¹), and displays lower charge-transfer resistance than the single-phase oxides. In addition, the composite retains >94% of its current over 24 h, indicating good durability. These results suggest that ferrite–tungstate coupling can be an effective strategy to non-noble OER catalysts.