Sensitive Glucose Biosensor Based on ZnO/CuO Nanorods

ZnO/CuO nanorods (NRs) were synthesized in two stages to fabricate highly sensitive, stabilized, and ultrafast nonenzymatic glucose biosensors. The first stage was a simple low-cost two-step anodization method, and the second stage involved modification with ZnO NRs by a chemical bath deposition method. The obtained NRs were analyzed by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy, photoluminescence spectroscopy (PL), and electrical studies. The XRD patterns of pure CuO NRs show that all peaks may be attributed to the monoclinic phase of CuO. However, the XRD patterns of the ZnO/CuO heterojunctions show a hexagonal phase structure for the ZnO NRs. The ZnO hexagonal NRs are densely interwoven with CuO NRs with lengths of 200–300 nm, according to FE-SEM micrographs. The PL emission spectra were found to be in the 406 nm range. This corresponded to an increase in the energy gap to 3.1 eV. The I–V characteristics of the biosensors were measured and evaluated at various glucose concentrations to determine their sensitivity and repeatability. The modified electrode achieved a wide linear range from 0.5 mM to 2 mM with a very low limit of detection (LOD) of 0.11 μM. The developed sensor had high sensitivity of 2225.5 mA mM^–1 cm^–2. This result confirms that the sensor has considerable potential as a high-performance nonenzymatic glucose sensor using a simple, low-cost, and novel sensor design.