New route for the synthesis of nickel (II) oxide nanostructures and its application as non-enzymatic glucose sensor

Sonoelectrochemistry is a technique that allows studying the effects of ultrasonic radiation on electrochemical systems. This technique is clean, inexpensive, improves the activation of the electrode surface and enables short synthesis times. In this context, this study uses sonoelectrochemistry to produce nickel oxide nanostructures, which will be proposed as an efficient and reliable glucose sensing device enzyme-free. For this, nickel oxide nanostructures have been electrochemically grown by ultrasound-assisted anodization of nickel foils in a solution composed of: ethylene glycol, ammonium chloride (0.5 wt% of NH₄Cl) and 5.0 wt% of H₂O solution. The anodization experiments were carried out using ultrasonic waves (37 kHz, 60 W) at different potentials (50 and 75 V), different temperatures (50 °C and 75 °C) and 900 s as anodization time. The process was carried out using a two-electrode system. The nanostructured NiO layers obtained were analyzed SEM, XRD and EDX for morphology, crystalline structure and chemical composition, respectively. The electrocatalytic activity of nanostructured NiO in the glucose oxidation reaction was studied by linear sweep voltammetry (LSV). From this technique, it was possible to determine the kinetic parameters that allow proposing a mechanism by which the glucose oxidation process takes place. The sensitivity (206.9 μA mM⁻¹ cm⁻²), the limit of detection (LOD, 1.16 μM), the limit of quantification (LOQ, 3.87 μM), the linear working range of the proposed electrode (0.1 mM ≤ [Glucose] ≤ 10 mM) and the response time (6 s), were determined. Finally, it was established that the nanostructured NiO electrode doesn't respond to different interferences (e.g. ascorbic, uric acid and dopamine acid), confirming the selectivity of NiO nanostructures for glucose. So, the electrode proposed in this study, is a good candidate for to be used as a non-enzymatic amperometric glucose sensor due to the good merit figures and its simple synthesis by ultrasound-assisted anodization.