Fabrication of non-enzymatic copper oxide-based electrochemical sensor for glucose detection / Adam Tan Tiek Aun

Adam Tan , Tiek Aun (2024) Fabrication of non-enzymatic copper oxide-based electrochemical sensor for glucose detection / Adam Tan Tiek Aun. PhD thesis, Universiti Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (262Kb)
	PDF (Thesis PhD) Restricted to Repository staff only until 31 December 2026. Download (4Mb)

Abstract

In the present study, three non-enzymatic copper-based sensors namely Cu oxide, Cu Ag oxide, and lactate templated Cu oxide were developed for the detection of glucose. The Cu oxide was prepared by the electrochemical anodization of a clean copper foil. The Cu Ag oxide and lactate templated Cu oxide were prepared by the electrodeposition of Cu Ag or lactate templated Cu on to a carbon paste electrode, followed by electrochemical oxidation in 0.1 M NaOH. The parameters of the synthesis process of all three glucose sensors were screened using 2k factorial design of experiments, then optimized using a central composite design of experiments. Chronoamperometry was used to measure the current density at the glucose sensor as a function of glucose concentration in the electrolyte and the sensitivity to glucose is used as a measure of the performance. It was found that lactate templated Cu oxide prepared at optimum conditions has the highest average sensitivity of 522.77 μA cm-2 mM-1. On the other hand, the Cu Ag oxide prepared at optimum conditions has the lowest average sensitivity of 191.33 μA cm-2 mM-1. The Cu oxide prepared at optimum conditions has a good sensitivity of 422.91 μA cm-2 mM-1. The Cu oxide, Cu Ag oxide, and lactate templated Cu oxide were then characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The CV study shows that the oxidation of glucose on all three sensors is limited by kinetics. The EIS study shows that increasing the concentration of glucose in the electrolyte lowers the charge transfer resistance between the glucose molecule and the Cu oxide, Cu Ag oxide, and lactate templated Cu oxide. The FESEM images show the glucose sensors prepared at optimized parameters have better coverage of the backing current collector electrode with unique nanostructures that increase the surface area at which the glucose can be oxidized. EDX analysis show that Cu oxide, Cu Ag oxide, and lactate Cu oxide prepared at optimum parameters all have a notably higher ratio of O to Cu. XRD analysis shows the crystal planes of the species of Cu, Ag, and C. The Cu oxide, Cu Ag oxide, and lactate templated Cu oxide have also used to measure the sugar content of several soft drinks. All three tend to slightly overestimate the sugar content likely due to the soft drinks containing other oxidizable substances such as colouring. The stability of the Cu oxide, Cu Ag oxide, and lactate templated Cu oxide have also been checked by using to measure glucose once every day for ten days. All the sensors have a general downward trend and the average drop in current density after 10 days for Cu oxide electrode is 9.96 %, Cu Ag oxide is 27.10 %, and lactate templated Cu oxide is 31.36 %. The Cu oxide, Cu Ag oxide, and lactate templated Cu oxide was also subjected to a constant potential of 0.5 V for 12 hours in solution of 6.04 mM glucose in 0.1 M NaOH. This resulted in the current density steadily dropping and the average drop in current density after 12 hours for Cu oxide is 30 %, Cu Ag oxide is 40.28%, and lactate templated Cu oxide is 44.91 %.

Actions (For repository staff only : Login required)