A Facile Method for Synthesizing Cobalt Oxide Nanoparticles to Create a Highly Sensitive Non-Enzyme Glucose Sensor

In this study, an electrochemical non-enzymatic glucose sensor based on cobalt oxide was developed using a simple chemical bath deposition method. The as-synthesized material exhibited no significant sensitivity; the latter emerged only after subsequent electrochemical activation. To the best of our knowledge, this is the first report demonstrating the successful application of electrochemical activation to achieve enhanced sensitivity. An X-ray diffraction analysis confirmed that a single-phase Co₂(OH)₂(CO₃) material was obtained immediately after synthesis, which was subsequently transformed into Co₃O₄ nanoparticles during electrochemical activation. SEM and TEM analyses revealed that the synthesized particles initially exhibited a nanorod structure, which evolved into a highly dispersed form after activation. The non-enzymatic glucose sensor based on the electrochemically activated material demonstrated excellent glucose sensitivity of 33,245 µA mM^-1 cm^-2 within the linear range of 0-0.5 mM, with a detection limit (LOD) of 5 µM. The starting material remained stable for over 12 months under ambient storage conditions and regained its high sensitivity following electrochemical activation.