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<p>Zinc-doped manganese ferrite nanoparticles (Zn<sub>0.4</sub>Mn<sub>0.6</sub>Fe<sub>2</sub>O<sub>4</sub>) were successfully synthesized via the sol–gel method using polyvinyl alcohol as a stabilizing agent to ensure uniform particle growth and controlled morphology. Structural and surface analyses (XRD, ATR-FTIR, XPS, HRTEM, FESEM, EDS, and BET) confirmed a single-phase cubic spinel structure (<i>Fd3m</i>) with lattice expansion due to Zn<sup>2+</sup> incorporation and redistribution of Fe<sup>3+</sup> ions between tetrahedral and octahedral sites. XPS results revealed the coexistence of mixed-valence states of Fe and Mn and an increase in oxygen vacancies, which enhanced surface reactivity. Despite a decrease in surface area, the nanoparticles maintained a mesoporous structure favorable for electrocatalysis. Morphological studies indicated compact and uniformly distributed nanoparticles with reduced crystallinity upon Zn doping. Electrochemical studies in 1&#xa0;M KOH demonstrated excellent hydrogen evolution reaction (HER) activity, with the Zn<sub>0.4</sub>Mn<sub>0.6</sub>Fe<sub>2</sub>O<sub>4</sub>/NF electrode achieving a cathodic current density of 116.41&#xa0;mA cm<sup>−2</sup> at −&#xa0;1.5&#xa0;V and a low overpotential of 215.1 mV at 10&#xa0;mA cm<sup>−2</sup>. Electrochemical impedance spectroscopy (EIS) confirmed a substantial reduction in charge-transfer resistance (R<sub>ct</sub>), indicating accelerated HER kinetics. DFT and Hirshfeld analyses revealed abundant active sites and strong Zn–Fe/Mn interactions promoting charge transfer. These results highlight Zn<sub>0.4</sub>Mn<sub>0.6</sub>Fe<sub>2</sub>O<sub>4</sub> as an efficient, non-noble, and cost-effective catalyst for sustainable hydrogen production.</p>

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Structural, Electrochemical, and Characterization Studies of ZnMnFe2O4 Nanoparticles Synthesized Via Sol–Gel Method for Hydrogen Evolution Reaction

  • 期刊论文

  • 发表日期：

    2025年11月10日

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  • H. Nady,
  • Ibraheem O. Ali,
  • Ebtsam K. Alenezy,
  • Ahmed A. Elhenawy,
  • H. H. Mohamed

摘要

Zinc-doped manganese ferrite nanoparticles (Zn0.4Mn0.6Fe2O4) were successfully synthesized via the sol–gel method using polyvinyl alcohol as a stabilizing agent to ensure uniform particle growth and controlled morphology. Structural and surface analyses (XRD, ATR-FTIR, XPS, HRTEM, FESEM, EDS, and BET) confirmed a single-phase cubic spinel structure (Fd3m) with lattice expansion due to Zn2+ incorporation and redistribution of Fe3+ ions between tetrahedral and octahedral sites. XPS results revealed the coexistence of mixed-valence states of Fe and Mn and an increase in oxygen vacancies, which enhanced surface reactivity. Despite a decrease in surface area, the nanoparticles maintained a mesoporous structure favorable for electrocatalysis. Morphological studies indicated compact and uniformly distributed nanoparticles with reduced crystallinity upon Zn doping. Electrochemical studies in 1 M KOH demonstrated excellent hydrogen evolution reaction (HER) activity, with the Zn0.4Mn0.6Fe2O4/NF electrode achieving a cathodic current density of 116.41 mA cm−2 at − 1.5 V and a low overpotential of 215.1 mV at 10 mA cm−2. Electrochemical impedance spectroscopy (EIS) confirmed a substantial reduction in charge-transfer resistance (Rct), indicating accelerated HER kinetics. DFT and Hirshfeld analyses revealed abundant active sites and strong Zn–Fe/Mn interactions promoting charge transfer. These results highlight Zn0.4Mn0.6Fe2O4 as an efficient, non-noble, and cost-effective catalyst for sustainable hydrogen production.