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<p>NiMn nanoparticle-embedded carbon nanofibers (NiMn-CNFs) were synthesized via electrospinning of a Ni(II) acetate / Mn(II) acetate/poly (vinyl alcohol) sol–gel followed by carbonization at 800&#xa0;°C (2&#xa0;°C&#xa0;min⁻<sup>1</sup>, 6&#xa0;h) under nitrogen, and evaluated as Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Raman spectroscopy confirmed partial graphitization of the carbon framework (<i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> = 0.855 for NiMn-CNF versus 0.896 for pristine CNF), indicating that NiMn incorporation promotes catalytic graphitization and enhances electronic conductivity. Electrochemical impedance spectroscopy (EIS) on symmetric dummy cells revealed that NiMn-CNF achieves the lowest charge-transfer resistance (<i>R</i><sub>ct</sub> = 13.3&#xa0;Ω) among all tested configurations, compared with Ni-CNF (<i>R</i><sub>ct</sub> = 23.2&#xa0;Ω), Mn-CNF (41.4&#xa0;Ω), and bare CNF (140.0&#xa0;Ω), demonstrating a genuine synergistic electrocatalytic effect of the bimetallic Ni–Mn combination. The corresponding DSSCs assembled with NiMn-CNF counter electrodes (<i>n</i> = 3 independent cells, AM&#xa0;1.5G, 100&#xa0;mW&#xa0;cm⁻<sup>2</sup>) achieved a power conversion efficiency of PCE = 4.21%, open-circuit voltage <i>V</i><sub>oc</sub> = 0.739&#xa0;V, short-circuit current density <i>J</i><sub>sc</sub> = 10.65&#xa0;mA&#xa0;cm⁻<sup>2</sup>, and fill factor <i>FF</i> = 0.535. These values represent a significant improvement over the control electrodes (bare CNF: 1.66%; Mn-CNF: 1.89%; Ni-CNF: 2.71%) and correspond to 71% of the Pt reference efficiency (5.94%) fabricated under identical conditions. The results demonstrate that the synergistic reduction in <i>R</i><sub>ct</sub> drives simultaneous improvements in <i>J</i><sub>sc</sub> and <i>FF</i>, confirming that NiMn-CNF is a scalable, cost-effective alternative to platinum for DSSC counter electrode applications.</p>

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Engineering bimetallic NiMn nanoparticle-embedded carbon nanofibers via electrospinning as efficient Pt-free counter electrodes for dye-sensitized solar cells

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • Maab Falah Hasan,
  • Noor Fawzi Shafiq,
  • Tamadhur Mohammed Sarhan,
  • Qusay Abdulsattar Mohammed,
  • Saif B. Mohammed,
  • Ali Kareem Alywee,
  • Saad Maadh Alhiti

摘要

NiMn nanoparticle-embedded carbon nanofibers (NiMn-CNFs) were synthesized via electrospinning of a Ni(II) acetate / Mn(II) acetate/poly (vinyl alcohol) sol–gel followed by carbonization at 800 °C (2 °C min⁻1, 6 h) under nitrogen, and evaluated as Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Raman spectroscopy confirmed partial graphitization of the carbon framework (ID/IG = 0.855 for NiMn-CNF versus 0.896 for pristine CNF), indicating that NiMn incorporation promotes catalytic graphitization and enhances electronic conductivity. Electrochemical impedance spectroscopy (EIS) on symmetric dummy cells revealed that NiMn-CNF achieves the lowest charge-transfer resistance (Rct = 13.3 Ω) among all tested configurations, compared with Ni-CNF (Rct = 23.2 Ω), Mn-CNF (41.4 Ω), and bare CNF (140.0 Ω), demonstrating a genuine synergistic electrocatalytic effect of the bimetallic Ni–Mn combination. The corresponding DSSCs assembled with NiMn-CNF counter electrodes (n = 3 independent cells, AM 1.5G, 100 mW cm⁻2) achieved a power conversion efficiency of PCE = 4.21%, open-circuit voltage Voc = 0.739 V, short-circuit current density Jsc = 10.65 mA cm⁻2, and fill factor FF = 0.535. These values represent a significant improvement over the control electrodes (bare CNF: 1.66%; Mn-CNF: 1.89%; Ni-CNF: 2.71%) and correspond to 71% of the Pt reference efficiency (5.94%) fabricated under identical conditions. The results demonstrate that the synergistic reduction in Rct drives simultaneous improvements in Jsc and FF, confirming that NiMn-CNF is a scalable, cost-effective alternative to platinum for DSSC counter electrode applications.