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<p>This work highlights the development of nanocrystalline ZnMn<sub>2</sub>O<sub>4</sub>, synthesized via a sol–gel route, as a visible-light-active photocatalyst for hydrogen production. Structural characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and FT-IR spectroscopy confirmed the formation of a single-phase cubic spinel structure. Scanning electron microscopy (SEM) revealed grains with uniform morphology, while the&#xa0;BET analysis showed a specific surface area of 27.75 m<sup>2</sup>/g and a pore volume of 0.2 cm<sup>3</sup>/g. The material exhibits an optical bandgap of 1.33&#xa0;eV, attributed to Mn<sup>3+</sup> 3d orbital splitting, and displays p-type behavior, with a flat band potential (E<sub>fb</sub>) of 0.18&#xa0;V vs. SCE, as determined from capacitance-potential measurements. The current–potential profile resembles a chemical diode, supporting a redox potential near − 0.7&#xa0;V vs. SCE and low hydrogen overvoltage. Under optimal conditions (pH ~ 12, 50&#xa0;°C, light flux of 28 mW/cm<sup>2</sup>), ZnMn<sub>2</sub>O<sub>4</sub> achieved a hydrogen evolution rate of 0.32&#xa0;μmol&#xa0;min<sup>−1</sup>&#xa0;g<sup>−1</sup> and a quantum efficiency of 0.79% using S<sub>2</sub>O<sub>3</sub><sup>2−</sup> as a reducing agent. ZnMn<sub>2</sub>O<sub>4</sub> demonstrated excellent stability and reusability over successive runs. These findings highlight the catalyst's potential as an affordable material for solar-powered hydrogen production, paving the way for efficient renewable energy systems.</p>

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Enhanced visible light photocatalytic H2 production on ZnMn2O4

  • 期刊论文

  • 发表日期：

    2025年2月13日

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  • S. Douafer,
  • H. Lahmar,
  • M. Benamira,
  • R. Laouici,
  • A. Sahmi,
  • M. Trari

摘要

This work highlights the development of nanocrystalline ZnMn2O4, synthesized via a sol–gel route, as a visible-light-active photocatalyst for hydrogen production. Structural characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and FT-IR spectroscopy confirmed the formation of a single-phase cubic spinel structure. Scanning electron microscopy (SEM) revealed grains with uniform morphology, while the BET analysis showed a specific surface area of 27.75 m2/g and a pore volume of 0.2 cm3/g. The material exhibits an optical bandgap of 1.33 eV, attributed to Mn3+ 3d orbital splitting, and displays p-type behavior, with a flat band potential (Efb) of 0.18 V vs. SCE, as determined from capacitance-potential measurements. The current–potential profile resembles a chemical diode, supporting a redox potential near − 0.7 V vs. SCE and low hydrogen overvoltage. Under optimal conditions (pH ~ 12, 50 °C, light flux of 28 mW/cm2), ZnMn2O4 achieved a hydrogen evolution rate of 0.32 μmol min−1 g−1 and a quantum efficiency of 0.79% using S2O32− as a reducing agent. ZnMn2O4 demonstrated excellent stability and reusability over successive runs. These findings highlight the catalyst's potential as an affordable material for solar-powered hydrogen production, paving the way for efficient renewable energy systems.