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<p>In this work, new electrocatalysts of SnO₂/Pd/PdO, Ni/NiO/Pd/PdO, and Ni/NiO/SnO<sub>2</sub>/Pd/PdO were prepared and thoroughly characterized for the methanol oxidation reaction (MOR) in direct methanol fuel cells. Exact quantitative insight into the composite formation was obtained from structural and morphological characterizations. The crystallite size of the active Pd phase, obtained from Williamson-Hall plots, showed a formation trend that increased from 6.75&#xa0;nm in SnO<sub>2</sub>/Pd/PdO to 13.38&#xa0;nm for the fully integrated Ni/NiO/SnO<sub>2</sub>/Pd/PdO composite, using coupled X-ray diffraction (XRD) analysis and further corroborated through Williamson-Hall calculations. This integration in structure gave rise to a positive lattice strain (2.84 × 10<sup>− 3</sup>) and the lattice constant was also increased (a = 3.902 Å). FESEM and EDX morphological studies indicated largely isolated nanoparticle networks resulting from the incorporation of SnO<sub>2</sub> as a dispersing agent, leading to a reduction in particle size from ~ 51&#xa0;nm (in Ni/NiO/Pd/PdO) to an optimum range of 30–46&#xa0;nm, thus preventing the aggregation of Pd/PdO. A series of electrochemical characterizations showed that the Ni/NiO/SnO<sub>2</sub>/Pd/PdO composite affords excellent electrocatalytic performance with a peak current density up to 62.6&#xa0;mA/cm<sup>2</sup> and an activation energy value as low as 28.79&#xa0;kJ/mol. This catalytic activity is far superior to recently reported benchmark catalysts such as PdNiAg nanoparticles (43.92&#xa0;mA/cm<sup>2</sup>) and bare Pd/GC (5&#xa0;mA/cm<sup>2</sup>), mainly owing to increased CO tolerance and a highly efficient diffusion-controlled oxidation mechanism. In addition, the enhanced catalyst showed excellent stability and reproducibility with 98% retention of its initial peak current after 20 cycles. The superior performance is attributed to the strong synergistic effect and charge transfer dynamics between Ni/NiO, SnO<sub>2</sub>, and Pd/PdO, as well as abundant active sites preventing catalyst poisoning, indicating a promising anode candidate for practical DMFC applications.</p> Graphical Abstract <p></p>

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Engineering the Highly Efficient Electrocatalyst Based on Pd and Metal Oxide Composites for Methanol Electrooxidation

  • 期刊论文

  • 发表日期：

    2026年4月27日

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  • Ramin Kamali,
  • Ali Reza Rezvani,
  • Sania Saheli

摘要

In this work, new electrocatalysts of SnO₂/Pd/PdO, Ni/NiO/Pd/PdO, and Ni/NiO/SnO2/Pd/PdO were prepared and thoroughly characterized for the methanol oxidation reaction (MOR) in direct methanol fuel cells. Exact quantitative insight into the composite formation was obtained from structural and morphological characterizations. The crystallite size of the active Pd phase, obtained from Williamson-Hall plots, showed a formation trend that increased from 6.75 nm in SnO2/Pd/PdO to 13.38 nm for the fully integrated Ni/NiO/SnO2/Pd/PdO composite, using coupled X-ray diffraction (XRD) analysis and further corroborated through Williamson-Hall calculations. This integration in structure gave rise to a positive lattice strain (2.84 × 10− 3) and the lattice constant was also increased (a = 3.902 Å). FESEM and EDX morphological studies indicated largely isolated nanoparticle networks resulting from the incorporation of SnO2 as a dispersing agent, leading to a reduction in particle size from ~ 51 nm (in Ni/NiO/Pd/PdO) to an optimum range of 30–46 nm, thus preventing the aggregation of Pd/PdO. A series of electrochemical characterizations showed that the Ni/NiO/SnO2/Pd/PdO composite affords excellent electrocatalytic performance with a peak current density up to 62.6 mA/cm2 and an activation energy value as low as 28.79 kJ/mol. This catalytic activity is far superior to recently reported benchmark catalysts such as PdNiAg nanoparticles (43.92 mA/cm2) and bare Pd/GC (5 mA/cm2), mainly owing to increased CO tolerance and a highly efficient diffusion-controlled oxidation mechanism. In addition, the enhanced catalyst showed excellent stability and reproducibility with 98% retention of its initial peak current after 20 cycles. The superior performance is attributed to the strong synergistic effect and charge transfer dynamics between Ni/NiO, SnO2, and Pd/PdO, as well as abundant active sites preventing catalyst poisoning, indicating a promising anode candidate for practical DMFC applications.

Graphical Abstract