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<p>We report a sol–gel fabrication of hydroxyapatite (HAP), cobalt oxide (Co<sub>3</sub>O<sub>4</sub>), and a HAP/Co<sub>3</sub>O<sub>4</sub> nanocomposite engineered as supercapacitor (SC) electrodes. Structural (XRD/FTIR), morphological (FESEM/EDX), and surface chemical (XPS) analyses confirm the phase-pure hexagonal HAP and spinel Co<sub>3</sub>O<sub>4</sub> with intimate interfacial contact in the composite. XPS reveals mixed Co<sup>2+</sup>/Co<sup>3+</sup> states and hydroxylated oxygen species, which are favorable for fast redox kinetics. In 6 M KOH symmetric two-electrode cells, cyclic voltammetry demonstrates pseudocapacitive behavior with b-values progressing from 0.68 (HAP) and 0.71 (Co<sub>3</sub>O<sub>4</sub>) to 0.78 (HAP/Co<sub>3</sub>O<sub>4</sub>); the capacitive contribution at 100 mV s<sup>−1</sup> rises to 67% for the composite, indicating a shift toward surface-controlled charge storage. Galvanostatic charge/discharge yields for HAP/Co<sub>3</sub>O<sub>4</sub> a specific capacitance of 281.07 F g<sup>−1</sup> and an energy density of 19.12 Wh kg<sup>−1</sup> at 0.5 A g<sup>−1</sup>, surpassing the single-component electrodes. Electrochemical impedance spectroscopy attributes the performance gains to reduced resistances (R<sub>ESR</sub> = 5.04 Ω; R<sub>ct</sub> = 11.28 Ω) relative to HAP and Co<sub>3</sub>O<sub>4</sub> alone, reflecting enhanced electron/ion transport through the composite architecture. Durability testing over 5000 cycles confirms robust stability with 90.91% capacitance retention. These results demonstrate that coupling dielectric HAP with redox-active Co<sub>3</sub>O<sub>4</sub> synergistically improves active-site accessibility, interfacial charge transfer, and rate capability, positioning HAP/Co<sub>3</sub>O<sub>4</sub> as a promising, low-cost electrode for high-power, durable SCs.</p>

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Sol–gel-derived hydroxyapatite/Co3O4 hybrid nanostructures as advanced electrodes for energy storage

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Waqid Al-Mussawi,
  • Muktha Eti,
  • Tanmoy Prida,
  • S. Radhika,
  • Mutabar Latipova,
  • Akmal Abilkasimov,
  • Ruslanbek Siddikov,
  • M. A. Diab,
  • Aseel Smerat,
  • Mounir M. Bekhit,
  • Ehab I. Taha

摘要

We report a sol–gel fabrication of hydroxyapatite (HAP), cobalt oxide (Co3O4), and a HAP/Co3O4 nanocomposite engineered as supercapacitor (SC) electrodes. Structural (XRD/FTIR), morphological (FESEM/EDX), and surface chemical (XPS) analyses confirm the phase-pure hexagonal HAP and spinel Co3O4 with intimate interfacial contact in the composite. XPS reveals mixed Co2+/Co3+ states and hydroxylated oxygen species, which are favorable for fast redox kinetics. In 6 M KOH symmetric two-electrode cells, cyclic voltammetry demonstrates pseudocapacitive behavior with b-values progressing from 0.68 (HAP) and 0.71 (Co3O4) to 0.78 (HAP/Co3O4); the capacitive contribution at 100 mV s−1 rises to 67% for the composite, indicating a shift toward surface-controlled charge storage. Galvanostatic charge/discharge yields for HAP/Co3O4 a specific capacitance of 281.07 F g−1 and an energy density of 19.12 Wh kg−1 at 0.5 A g−1, surpassing the single-component electrodes. Electrochemical impedance spectroscopy attributes the performance gains to reduced resistances (RESR = 5.04 Ω; Rct = 11.28 Ω) relative to HAP and Co3O4 alone, reflecting enhanced electron/ion transport through the composite architecture. Durability testing over 5000 cycles confirms robust stability with 90.91% capacitance retention. These results demonstrate that coupling dielectric HAP with redox-active Co3O4 synergistically improves active-site accessibility, interfacial charge transfer, and rate capability, positioning HAP/Co3O4 as a promising, low-cost electrode for high-power, durable SCs.