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<p>We report the development of a highly sensitive voltammetric sensor for the detection of ascorbic acid (AA) based on a reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposite modified glassy carbon electrode (GCE). Graphene oxide (GO) was synthesized via an improved Hummers method and subsequently reduced using zinc powder under hydrothermal conditions, followed by NaOH treatment and ethanol washing. The resulting rGO-ZnO nanocomposite exhibited uniformly distributed ZnO nanoparticles anchored on rGO sheets, as confirmed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier-transform infrared spectroscopy (FTIR). Electrochemical characterization using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) revealed outstanding electrocatalytic performance toward AA oxidation. The rGO-ZnO/GCE sensor displayed a wide linear detection range of 0.23–2.66 pM by CV and DPV, with ultra-low limits of detection (LOD) 0.16 ± 0.04 pM and 0.30 ± 0.04 pM, and limit of quantification (LOQ) of 0.53 ± 0.04 pM and 0.90 ± 0.04 pM. The rGO–ZnO modified electrode exhibited high sensitivity, calculated as 2942 µA mol<sup>−1</sup> L cm<sup>−2</sup> (CV) and 3502 µA mol<sup>−1</sup> L cm<sup>−2</sup> (DPV). The electrochemically active surface area (ECSA) was calculated to be 0.024 cm<sup>2</sup> based on the Randles–Ševčík equation. The sensor demonstrated long-term stability over 45 days, and high recovery values (91–97%) in spiked real samples. These results highlight the potential of the rGO-ZnO nanohybrid for advanced electrochemical sensing platforms targeting low-concentration biomarker detection.</p> Graphical Abstract <p></p>

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Electrocatalytic Sensing of Ascorbic Acid with a rGO-ZnO Nanocomposite: Towards Ultra-Trace Detection

  • 期刊论文

  • 发表日期：

    2025年8月14日

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  • Anil A. Powar,
  • Anita K. Tawade,
  • Kiran Kumar K. Sharma,
  • Dattatraya J. Sathe,
  • Vishnu Dev Gupta,
  • Shivaji N. Tayade

摘要

We report the development of a highly sensitive voltammetric sensor for the detection of ascorbic acid (AA) based on a reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposite modified glassy carbon electrode (GCE). Graphene oxide (GO) was synthesized via an improved Hummers method and subsequently reduced using zinc powder under hydrothermal conditions, followed by NaOH treatment and ethanol washing. The resulting rGO-ZnO nanocomposite exhibited uniformly distributed ZnO nanoparticles anchored on rGO sheets, as confirmed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier-transform infrared spectroscopy (FTIR). Electrochemical characterization using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) revealed outstanding electrocatalytic performance toward AA oxidation. The rGO-ZnO/GCE sensor displayed a wide linear detection range of 0.23–2.66 pM by CV and DPV, with ultra-low limits of detection (LOD) 0.16 ± 0.04 pM and 0.30 ± 0.04 pM, and limit of quantification (LOQ) of 0.53 ± 0.04 pM and 0.90 ± 0.04 pM. The rGO–ZnO modified electrode exhibited high sensitivity, calculated as 2942 µA mol−1 L cm−2 (CV) and 3502 µA mol−1 L cm−2 (DPV). The electrochemically active surface area (ECSA) was calculated to be 0.024 cm2 based on the Randles–Ševčík equation. The sensor demonstrated long-term stability over 45 days, and high recovery values (91–97%) in spiked real samples. These results highlight the potential of the rGO-ZnO nanohybrid for advanced electrochemical sensing platforms targeting low-concentration biomarker detection.

Graphical Abstract