Reduced Graphene Oxide and Nickel Nanoparticle Nanocomposites: Tailoring the Nanoparticle Size for Enhanced Glucose Electrochemical Sensors

High Resolution Image Download MS PowerPoint Slide In this study, we developed an electrochemical glucose sensor using Ni nanoparticles supported on reduced graphene oxide (rGO) with or without polyvinylpyrrolidone (PVP) as a stabilizer. The rGO/Ni nanocomposites were synthesized via a modified polyol method, producing metallic Ni with a face-centered cubic structure. By adjusting the reducing agent ratio, it was possible to control the nanoparticle size and distribution, achieving an average diameter of 4.0 ± 0.9 nm for a Ni 2+:NaBH 4 molar ratio of 1:12 (rGO/Ni-4). The electrochemical behavior of the rGO/Ni nanocomposite was evaluated using cyclic voltammetry and chronoamperometry, demonstrating significant activity for glucose oxidation in alkaline media. The sensitivities of the nanocomposite thin films deposited on indium tin oxide substrates were directly influenced by Ni nanoparticle size and by the presence of PVP. The rGO/Ni/PVP-4 nanocomposite exhibited the highest sensitivity (48.6 ± 2.8 μA (mmol L –1 ) −1 ), reaching a very low limit of detection of 0.26 μmol L –1 . In addition, the optimized Ni-based sensor showed electroactivity across a wide range of glucose concentrations (1–1000 μmol L –1 ) and good reproducibility, although its reuse was limited due to partial loss of the active material. The combination of PVP-assisted stabilization of the nanoparticles and the high conductivity of rGO led to a synergistic improvement in surface area, redox cycling, and electron transfer. These properties make the rGO/Ni/PVP-4 nanocomposite a promising candidate for low-cost, disposable electrochemical sensors for glucose monitoring in biomedical or environmental applications.