On the Role of MWCNTs for the Effective Detection of Glucose Using MWCNTs/NiO/MWCNTs Stacks on Carbon Paper Electrodes

Non‐enzymatic high‐performance glucose sensors are important due to their stability and low cost. Nickel oxide and its composites with various materials such as multi‐walled carbon nanotubes (MWCNTs) have emerged as a platform for non‐enzymatic glucose detection at micromolar concentrations. In this article, the reaction mechanism within a MWCNTs/NiO/MWCNTs stacked electrode system used for glucose detection is explored and elucidated. Micro‐Raman and ‐Xray Photoelectron Spectroscopy are used to track the changes associated with the chemical state of the MWCNTs in the composite electrode during the oxidation of glucose molecules. The results show that the presence of MWCNTs provides abundant active sites for the electrochemical reaction. The enhanced electron transfer improves sensor sensitivity as evidenced by distinct redox peaks in the cyclic voltammograms. We conclude that the MWCNTs used herewith provide an ultrahigh surface‐area‐to‐volume ratio for the adsorption of OH − ions from the alkaline medium, which, in turn, facilitates the formation of NiOOH from NiO. The NiOOH formed further acts as an oxidizing agent for glucose molecules, altering them to gluconolactone via a chemical reaction that produces hydrogen peroxide while regenerating NiO. The detailed understanding of the reaction mechanism underscores the significant role of MWCNTs in enhancing the efficiency and sensitivity of non‐enzymatic glucose sensors.