Enhanced Nonenzymatic Glucose Sensing Performance of CuO/Au-Decorated Multiwalled Carbon Nanotube Buckypaper

Abstract

Nonenzymatic electrochemical glucose sensors have attracted significant research interest owing to their superior stability, low cost, and independence from enzyme activity. In this study, buckypaper electrodes based on acid-treated multiwalled carbon nanotubes (a-MWCNTs) decorated with copper oxide (CuO) nanoparticles and gold (Au) nanoparticles were fabricated and systematically evaluated for nonenzymatic glucose sensing performance. MWCNTs were functionalized by acid treatment to introduce carboxyl and hydroxyl groups on the nanotube surface, followed by hydrothermal synthesis of CuO nanoparticles at various precursor concentrations (0.01, 0.03, and 0.05 M) and subsequent Au nanoparticle deposition by DC sputter coating. The morphological and structural properties of the fabricated nanocomposites were characterized by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Electrochemical performance was evaluated by cyclic voltammetry (CV) and chronoamperometry in 0.1 M NaOH electrolyte. A key finding of this study is that Au nanoparticle incorporation promotes the formation of clustered CuO morphologies on the MWCNT surface, a phenomenon not observed in Au-free electrodes, thereby increasing the electrode-specific surface area and enhancing electrocatalytic activity. The optimized 0.05 M CuO/Au@a-MWCNTbuckypaper electrode achieved a glucose sensitivity of 730 µA mM⁻¹ cm⁻², which was approximately 1.2 times higher than the Au-free counterpart (599 µA mM⁻¹ cm⁻²). The electrode demonstrated a linear detection range of 0–10 mM (R² = 0.996) and a limit of detection (LoD) of 0.18 mM. Selectivity tests under simulated blood conditions confirmed excellent discrimination against sucrose and lactose, though further testing against physiologically relevant interferents such as ascorbic acid, uric acid, and dopamine is warranted. These results demonstrate the potential of CuO/Au@a-MWCNTbuckypaper as a high-performance electrode material for nonenzymatic electrochemical glucose biosensors.