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<p>The methanol oxidation reaction (MOR) is a critical anodic process in direct methanol fuel cells (DMFCs), but its efficiency is limited by sluggish kinetics and catalyst poisoning. This study reports the fabrication of Ni-SnS/SnO<sub>2</sub> composite thin films via potentiostatic (chronoamperometric) electrodeposition followed by thermal annealing at 400&#xa0;°C. X-ray diffraction (XRD) analysis revealed the coexistence of tetragonal rutile SnO<sub>2</sub> and orthorhombic SnS phases, forming a composite structure. Atomic Force Microscopy (AFM) indicated increased surface roughness (RMS: 66.8&#xa0;nm vs. 50.7&#xa0;nm for pristine SnO<sub>2</sub>) and enlarged grain sizes (58&#xa0;nm vs. 20&#xa0;nm), consistent with XRD apparent crystallite size calculations. Mott-Schottky analysis confirmed n-type semiconductor behavior with increased carrier density (7.76 × 10<sup>22</sup> cm<sup>−</sup>³ vs. 11.6 × 10<sup>22</sup> cm<sup>−</sup>³) upon Ni incorporation. Electrochemical impedance spectroscopy (EIS) demonstrated reduced charge-transfer resistance (1.18 kΩ·cm² vs. 5.55 kΩ·cm²) for the composite material. Cyclic voltammetry in 0.1&#xa0;M NaOH revealed that while pristine SnO<sub>2</sub> exhibited negligible MOR activity, the Ni-mediated composite displayed a distinct oxidation peak at ~ 620 mV (vs. SCE) with current densities increasing with methanol concentration (9–19% (v/v)). These results indicate that SnS/SnO<sub>2</sub> composites prepared via NiSO<sub>4</sub>-mediated electrodeposition are promising electrocatalysts for alkaline MOR applications.</p> Graphical Abstract <p></p>

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Synthesis and characterization of SnO2 and Ni-SnS/SnO2 composite films for enhanced methanol oxidation reaction (MOR)

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Meriem Lakhdari,
  • Rania Kara,
  • Mouna Ghemid,
  • Houssem Eddine El Yamine Sakhraoui,
  • Abdelghani Rahal,
  • Achref Nouioua,
  • Wail Boureghdad,
  • Mohamed Trari

摘要

The methanol oxidation reaction (MOR) is a critical anodic process in direct methanol fuel cells (DMFCs), but its efficiency is limited by sluggish kinetics and catalyst poisoning. This study reports the fabrication of Ni-SnS/SnO2 composite thin films via potentiostatic (chronoamperometric) electrodeposition followed by thermal annealing at 400 °C. X-ray diffraction (XRD) analysis revealed the coexistence of tetragonal rutile SnO2 and orthorhombic SnS phases, forming a composite structure. Atomic Force Microscopy (AFM) indicated increased surface roughness (RMS: 66.8 nm vs. 50.7 nm for pristine SnO2) and enlarged grain sizes (58 nm vs. 20 nm), consistent with XRD apparent crystallite size calculations. Mott-Schottky analysis confirmed n-type semiconductor behavior with increased carrier density (7.76 × 1022 cm−³ vs. 11.6 × 1022 cm−³) upon Ni incorporation. Electrochemical impedance spectroscopy (EIS) demonstrated reduced charge-transfer resistance (1.18 kΩ·cm² vs. 5.55 kΩ·cm²) for the composite material. Cyclic voltammetry in 0.1 M NaOH revealed that while pristine SnO2 exhibited negligible MOR activity, the Ni-mediated composite displayed a distinct oxidation peak at ~ 620 mV (vs. SCE) with current densities increasing with methanol concentration (9–19% (v/v)). These results indicate that SnS/SnO2 composites prepared via NiSO4-mediated electrodeposition are promising electrocatalysts for alkaline MOR applications.

Graphical Abstract