Functional Channel of SWCNTs/Cu₂O/ZnO NRs/Graphene Hybrid Electrodes for Highly Sensitive Nonenzymatic Glucose Sensors

Abstract

The hybrid electrode of single-wall carbon nanotubes (SWCNTs)/Cu2O/ZnO nanorods (NRs)/graphene used on the current-response nonenzymatic glucose sensor was investigated herein, regarding the mechanism of the formation of functional channel. The synthesis of the hybrid electrode involved four steps. First, the graphene was grown by chemical vapor deposition (CVD) and then wet-transferred onto indium transparent oxide (ITO) glass. Second, a zinc oxide (ZnO) seed layer was sputtered onto the graphene/ITO glass, and ZnO NRs were gradually grown by the hydrothermal method. Third, the ZnO NRs were clad with cuprous oxide (Cu2O) by the electrochemical method. Fourth, the SWCNTs were dropped onto the Cu2O surface, with a Nafion surfactant. X-ray diffraction spectra, scanning electron microscopy spectra, Raman spectra, cyclic voltammograms, and amperometric response diagrams were used to verify the performance of the device. Results showed that sensitivity increased significantly from 11.2 to 289.8 μA mM–1 cm–2, linear range increased significantly from 0.6 to 11.1 mM, and the coefficient of determination (R 2) increased from 0.9766 to 0.9923, all by the addition of the SWCNTs/Cu2O functional channel mechanism and without graphene. When the graphene was added to the functional channel electrode, sensitivity increased again from 289.8 to 466.1 μA mM–1 cm–2 at low concentrations.

Learning from Nature: Constructing a Smart Bionic Structure for High‐Performance Glucose Sensing in Human Serums

“…In particular, the sensitivity value is not only superior to that of the binary counterparts (442.2 and 1052.6 µA mm −1 cm −2 for the NiF@GNSs and NiF@Co 3 O 4 NGs, respectively), but also even one to two orders of magnitude higher than the data of other ever reported non-enzymatic sensors for glucose detection (Table 1). [55][56][57][58][59][60][61][62][63][64][65][66] The increase of glucose concentrations causes the decline in the slope of fitting plots since the surface-controlled electrochemical oxidation of glucose is affected by the glucose concentration and the active sites on the surface of catalysts. As the glucose concentration rises, the number of available surface-active sites reduces and thus the increase in rate of currents slows down.…”

Applications of Non‐precious Transition Metal Oxide Nanoparticles in Electrochemistry

“…In the context of the aforementioned prominent challenges, these main guidelines can provide the ground for identifying the potential new TMO NPs as the viable candidates for replacing the present electrode substances: 1) dimension control synthesis of the TMOhetero-structures for achieving the optimized active sites [182,183], 2) establishing 2D shape of the single or few atomic layers of the transition metal elements through the epitaxial overgrowth of the secondary metals [184], 3) constructing the nano-composites with the carbon nanomaterials like carbon nanotubes (CNTs), activated carbon, graphene and so on to enhance their catalytic activity and conductivity, and attain monodispersivity with lower dimensional NPs [185,186], 4) generating the nanocomposites with other metals to gain higher catalytic activities and sensitivities for diverse sensor platforms [187], 5) understanding basic associations of the morphological structure, dimensions, compositions and catalytic activities of the transition metal/oxide nano-materials [188,189], 6) optimizing the multimetal or oxide nanomaterials for amplification of the catalytic activities, charge storage capacity, and the prolonged stability [190,191], and 7) selecting the substances and designing the new nanocomposites with other materials such as alloys, dopants, and core-shell structures for enhancing the new functionalities, higher conductivity, longer chemical durability, and higher surface areas [192][193][194].…”

Cost Effective Synthesis of Graphene Nanomaterials for Non-Enzymatic Electrochemical Sensors for Glucose: A Comprehensive Review

“…However, the direct growth of graphene onto metallic substrate electrode encloses a possibility the graphene to be contaminated with metallic impurities [ 57 ], influencing its electrochemical and electronic properties. So, different metallic conductive substrates, such as indium tin oxide (ITO), fluorine tin oxide (FTO) [ 58 ] and others have also been studied [ 32 , 59 ].…”

“…Chen et al [ 59 ] reported the direct growth of graphene onto Cu foil via CVD method, its spraying with poly(methyl methacrylate, PMMA) and then the PMMA/graphene transfer (via a wet transference process) onto the ITO. However, we deduce that this synthesis method reintroduces the transfer step that was disregarded according to the direct growth of graphene onto metallic foil.…”