Insight into the Electro-Oxidation Mechanism of Glucose and Other Carbohydrates by CuO-Based Electrodes

Abstract

In this work, a new hypothesis for the electrocatalytic behavior of CuO electrodes is presented. Different from the established mechanism, here we discuss why Cu species do not participate in the oxidation mechanism of carbohydrates. We show that hydroxyl ion adsorption and the semiconductive properties of the material play a more significant role in this process. The relationship between the flat band potential and the potential that begin oxidation suggests that the concentration of vacancies in the charge region acts upon the reactivity of the adsorbed hydroxyl ions through a partial charge transfer reaction. In the presence of carbohydrate molecules, the electron transfer is facilitated and involves the transfer of electrons from the adsorbed hydroxyl ions to the CuO film. This mechanism is fundamentally relevant since it helps the understanding of several experimental misleads. The results can also lead to obtaining better catalysts, since improvements in the material should focus on enhancing the semiconductive properties rather than the Cu/Cu redox transition. The results shed light on different aspects of carbohydrate molecules oxidation that could lead to novel applications and possibly a better description of other semiconductor mechanisms in electrocatalysis.

Highly sensitive non-enzymatic electrochemical glucose sensor based on dumbbell-shaped double-shelled hollow nanoporous CuO/ZnO microstructures

“…Instead, also in the absence of glucose, a plateau around 0.5-0.7 V vs. Ag/AgCl was observable. The capacitive nature of this plateau has been approved previously 52 which could be attributed to the adsorption of hydroxyl ions in the electrolyte to the surface of CuO/ZnO electrode as a p-type semiconductor. The sharp increase of the current after this plateau also could be attributed to the oxidation of these adsorbed hydroxyl species to O 2 in the high anodic potentials.…”

“…In the absence of glucose, the further oxidation of these adsorbed species caused the sharp current increase at the extreme of the anodic sweep. However, in the presence of glucose, some interactions of the analyte with the electrode surface was expectable 52 . According to interactions of glucose with the electrode surface, the amplification of the oxidation process of OH − species occurred and in turn, the current has been increased.…”

MOMSense: Metal-Oxide-Metal Elementary Glucose Sensor

“…On the other hand, a thorough analytical study of the electrochemical CuO system by Barragan et al . 69 pinpointed several controversies of the widely accepted mechanism above to justify a new hypothesis for the electrocatalytic behavior of CuO that claims little to no role of Cu 3+ species in the electro-oxidation process of glucose. Barragan et al .…”

Multisensor Systems by Electrochemical Nanowire Assembly for the Analysis of Aqueous Solutions

“…The electrochemical activities of different nanodendrite electrode surfaces prepared by DENA toward glucose oxidation were studied to evaluate the feasibility of their application for glucose sensing, Figures 5 – 7 . Non-enzymatic glucose electrochemical sensors have been presented and discussed in a number of recent reviews and articles (Toghill and Compton, 2010 ; Chen and Ostrom, 2015 ; Jin et al, 2015 ; Pourbeyram and Mehdizadeh, 2016 ; Liu et al, 2017 ; Quesada-González and Merkoçi, 2017 ; Shabnam et al, 2017 ; Barragan et al, 2018 ). The electrochemical measurements for the Au NW electrode were performed in a 0.1 M PBS at pH 7.2, Figure 5 .…”