Hierarchical CuO Nanorod‐Nanoparticle Homojunction for Enhanced Nonenzymatic Glucose Biosensing and Electrochemical Energy Storage Applications

ABSTRACT This study aims to fabricate a novel hierarchical copper oxide nanoparticles‐decorated copper oxide nanorod (CuO‐CuO) electrode on a fluorine‐doped tin oxide (FTO) coated glass substrate using a three‐step synthesis approach, comprising spin‐coating, hydrothermal growth, and a subsequent spin‐coating process. The resulting CuO‐CuO homojunction electrode was utilized as a highly sensitive, cost‐effective, nonenzymatic and noninvasive platform for glucose detection as well as electrochemical energy storage application. The surface morphology, particle size, internal structure and crystallinity of the fabricated electrodes were systematically investigated using field‐emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). In addition, the crystalline phase, structure, phase purity and optical band‐gap of the synthesized material were determined using X‐ray diffraction (XRD) and UV–visible spectroscopy. Cyclic voltammetry (CV), amperometric i − t and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate electrochemical performance of the fabricated electrodes. The CuO‐CuO NR demonstrated an excellent sensitivity of 5.33 mA mM −1 cm −2 over 0–0.325 mM linear detection range and 14.9 μM as a limit of detection (LOD). The effective surface area (ECSA) of the CuO NR and CuO‐CuO NR homojunction electrodes was further investigated to assess the effect of CuO nanoparticles decoration on the availability of electrochemically active sites. The hierarchical CuO‐CuO architecture holds considerable potential for emerging electrochemical energy‐storage applications, including high‐performance supercapacitors and rechargeable battery electrodes. This potential arises from its enlarged surface area, efficient charge‐transfer pathways, and high density of electrochemically active sites.