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<p>A mixed Mn–Zn ferrite spinel, (Mn<sub>0.5</sub>Zn<sub>0.5</sub>)Fe<sub>2</sub>O<sub>4</sub>, was synthesized by a conventional co-precipitation method followed by calcination and evaluated as a noble-metal-free electrocatalyst for the hydrogen evolution reaction in alkaline medium. X-ray diffraction confirmed the formation of a crystalline spinel ferrite phase, with characteristic reflections assigned to the cubic ferrite structure. Scanning electron microscopy revealed irregular agglomerated particles with rough surface features, while energy-dispersive X-ray elemental mapping confirmed the homogeneous distribution of Mn, Zn, Fe, and O throughout the analyzed regions. Electrochemical measurements performed in 1.0&#xa0;M KOH demonstrated that the (Mn<sub>0.5</sub>Zn<sub>0.5</sub>)Fe<sub>2</sub>O<sub>4</sub> electrode exhibits hydrogen evolution activity, requiring overpotentials of 67.5 and 404.7&#xa0;mV to reach current densities of 10 and 50&#xa0;mA&#xa0;cm⁻<sup>2</sup>. Tafel analysis yielded a slope of 0.817&#xa0;V dec⁻<sup>1</sup>, indicating that the reaction kinetics are mainly governed by interfacial charge-transfer and surface reaction limitations. Electrochemical impedance spectroscopy and Bode analysis showed a mixed resistive–capacitive response with distributed relaxation processes at the electrode/electrolyte interface. Direct hydrogen production measurements confirmed continuous H2 generation, with a production rate of 961.76&#xa0;μmol&#xa0;h⁻<sup>1</sup>. These findings demonstrate that (Mn<sub>0.5</sub>Zn<sub>0.5</sub>)Fe<sub>2</sub>O<sub>4</sub> is an active mixed-cation spinel ferrite electrode for alkaline hydrogen evolution and provide insight into the role of Mn–Zn–Fe oxide systems in noble-metal-free electrocatalysis.</p>

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Mixed-cation (Mn0.5Zn0.5)Fe2O4 spinel ferrite for sustainable hydrogen production via the alkaline hydrogen evolution reaction

  • 期刊论文

  • 发表日期：

    2026年7月7日

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  • Manel Kechouane,
  • Mohammed Wafik Khemici,
  • Amal Elfiad,
  • Soumia Benredouane,
  • Khadidja Boukhouidem,
  • Khaled Derkaoui,
  • Mohamed Azzaz,
  • Amirouche Hammouda,
  • Naïma Khemici-Doulache,
  • Toufik Hadjersi,
  • Mohamed Kechouane

摘要

A mixed Mn–Zn ferrite spinel, (Mn0.5Zn0.5)Fe2O4, was synthesized by a conventional co-precipitation method followed by calcination and evaluated as a noble-metal-free electrocatalyst for the hydrogen evolution reaction in alkaline medium. X-ray diffraction confirmed the formation of a crystalline spinel ferrite phase, with characteristic reflections assigned to the cubic ferrite structure. Scanning electron microscopy revealed irregular agglomerated particles with rough surface features, while energy-dispersive X-ray elemental mapping confirmed the homogeneous distribution of Mn, Zn, Fe, and O throughout the analyzed regions. Electrochemical measurements performed in 1.0 M KOH demonstrated that the (Mn0.5Zn0.5)Fe2O4 electrode exhibits hydrogen evolution activity, requiring overpotentials of 67.5 and 404.7 mV to reach current densities of 10 and 50 mA cm⁻2. Tafel analysis yielded a slope of 0.817 V dec⁻1, indicating that the reaction kinetics are mainly governed by interfacial charge-transfer and surface reaction limitations. Electrochemical impedance spectroscopy and Bode analysis showed a mixed resistive–capacitive response with distributed relaxation processes at the electrode/electrolyte interface. Direct hydrogen production measurements confirmed continuous H2 generation, with a production rate of 961.76 μmol h⁻1. These findings demonstrate that (Mn0.5Zn0.5)Fe2O4 is an active mixed-cation spinel ferrite electrode for alkaline hydrogen evolution and provide insight into the role of Mn–Zn–Fe oxide systems in noble-metal-free electrocatalysis.