Electrochemical Properties of Copper Oxides Obtained from Layered Copper Hydroxide Acetate for Nonenzymatic Glucose Sensing
Authors: Nomura Yuki , Togasaki Norihiro , Takimoto Daisuke , Hideshima Sho 
Published: December 2024

Nowadays, glucose sensing is a crucial role for capturing the status of diabetes, and its precise sensing directly contributes to prevent such diseases from exacerbating. While the use of enzymes such as glucose oxidase is known to be a major stream in glucose sensing. the issues of cost. Reusability. and chemical stability are still room for development. One of the non-enzyme system, copper oxides, would be a game-changer in place of enzymes.1 In addition to some great features which can address the aforementioned issues, copper oxides have a unique characteristic of their microstructure.1 Because the microstructure (surface area) greatly dictates the sensing ability, several literatures report the correlation between sensing ability and the microstructure of copper oxides. 2,3 With this keep in mind, we prepared several copper oxides with different morphology by using a one-pot fabrication process based on electrochemistry and investigate the effect of various morphologies of copper oxides on the glucose performance (Fig. 1A). We prepared copper oxides by reducing a layered copper hydroxide acetate (Cu2(OH)3Ac-) with various voltages.4

First, Cu(CH3COO)2・H2O was added into ultra-purified water and was allowed in a thermostatic bath at 60 ℃ for 30 h to obtain Cu2(OH)3Ac-.4 The resultant Cu2(OH)3Ac- was mixed with water and was drop casted onto a carbon paper. The obtained carbon paper incorporated with Cu2(OH)3Ac- was immersed in 0.1 M KHCO3 electrolyte and was exposed at the constant voltage of -1.2 V vs. Ag/AgCl for one hour to obtain copper oxide. (Figure. 1(A))
Figure 1(B) shows the cyclic voltammograms of carbon paper electrodes in the absence or presence of copper oxides in the electrolyte of 0.1 M NaOH with 5 mM glucose. For the carbon paper electrode, there is no oxidation current appeared in the voltage range of 0-0.8 V vs. Ag/AgCl, suggesting that the carbon paper itself is inert for electrochemical reactions in such voltage range. On the flipside, a significant oxidation peak appeared when the carbon paper incorporated with copper oxides was used. More importantly, the peak current has a strong relationship with glucose concentration (Figure 1(C)), suggesting the glucose concentration is electrochemically detectable. We will demonstrate and discuss the influence of the applied potential during the fabrication of copper oxides on the glucose response in the poster session.
Acknowledgements
The work was supported partly by Nippon Sheet Glass Foundation for Materials Science Engineering.
References
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Figure 1