NiO Nanoflowers for Non-Enzymatic Amperometric Detection of Glucose

Non-enzymatic glucose sensors employing nanostructured metal oxide materials are amongst the most extensively researched topics currently. Several transition metal oxides (TMOs), such as iron oxides (α-Fe2O3, γ-Fe2O3, Fe3O4, etc.), nickel oxide (NiO), copper oxide (CuO), chromium trioxide (CrO3), etc., have been utilized as enzyme-mimicking catalysts for glucose oxidation. Along with the use of different TMO materials, considerable efforts have been put into studying the impact of different morphologies of these materials. The literature shows that the flower and wire-shaped catalysts perform better due to their large surface area. This study presents the non-enzymatic glucose sensing properties of NiO nanoflower decorated glassy carbon electrodes (NiO NF@GCE). The central objective of this work is to shed light on the processes involved in the fabrication and characterization of glucose-sensing NiO nanoflowers on GCE. The amperometric detection of glucose shows a linear increase in current over physiologically relevant glucose concentrations ranging between 0 mM and 15 mM. The electrodes offer an excellent sensitivity of 281.69 µA mM^-1·cm^-2 and a limit of detection of 10 µM. The results show that the linear range of detection increases while the sensitivity decreases with an increase in the loading mass of the nanomaterial after a certain loading concentration. In addition, the electrodes showed high selectivity towards glucose in the presence of other interfering species, such as ascorbic acid, fructose, sucrose, and NaCl. The impact of loading concentration on the selectivity of NiO NF-modified electrodes shows a decrease in selectivity with the increase in loading of the nanomaterial after a certain optimal loading mass.