Synthesis and characterization of electrocatalytic graphene for electrochemical sensing and bioelectronics

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dc.contributor.authorOsikoya, Adeniyi Olugbenga
dc.contributor.promoterDikio, E. D., Prof.
dc.date.accessioned2023-06-28T00:26:53Z
dc.date.available2023-06-28T00:26:53Z
dc.date.issued2018-02
dc.descriptionD. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology.en_US
dc.description.abstractIn this study, few layer graphene (Gr) and heteroatom graphene (HGr) were synthesized by chemical vapour deposition (CVD) method. Acetylene gas was used as carbon source for the synthesis of graphene, while a mixture of nitrobenzene and dichloromethane (ratio 1:1) were used as both carbon and dopant sources for the synthesis of the heteroatom graphene (HGr). A mixture of argon and nitrogen gases were carefully combined and used as carrier gasses and purge for both the synthesis of graphene and the synthesis of heteroatom graphene. X-ray diffraction (XRD) characterized showed that the as synthesized materials were crystalline materials, Raman spectroscopy indicated that the synthesized materials consist of sp2 hybridized carbon atoms, while scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed that the synthesized materials possess regions of 2 to 7 nm of thickness. Transmission electron microscopy (TEM) characterization also showed that the synthesized heteroatom graphene possesses about 5 to 7 layers with about 2 nm thickness, and x-ray photoelectron spectroscopy (XPS) result showed the presence of nitrogen, oxygen and chlorine in the lattice of the synthesized heteroatom graphene while the synthesized material still retained about 80% sp2 hybridization. The synthesized materials were used in the fabrication of modified bioelectrodes for electrobiocatalytic biosensing of glucose and hydroquinone. The fabricated bioelectrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV characterization showed a diffusion-controlled electrode processes in al modified electrodes, while the EIS characterization showed the presence of both diffusion controlled and kinetic controlled impedance at the electrode-electrolyte interface. The fabricated GC/PEDOT-PSS/HGr/Lac modified bioelectrode exhibited a kinetic controlled impedance of 3150 Ω, while the fabricated GC/PEDOT-PSS/Gr/Lac modified bioelectrode exhibited a kinetic controlled impedance of 4138 Ω. Chronoamperometric experiments showed that the fabricated bioelectrodes exhibited swift electrobiocatalytic activity towards glucose and hydroquinone sensing respectively for graphene and heteroatom graphene. The graphene modified bioelectrode exhibited a linear response of 0.2 to 9.8 mM glucose concentration and a sensitivity of 87.0 μA/mM/cm2, while the heteroatom modified bioelectrode also exhibited a swift response to step by step addition of hydroquinone with a limit of detection of 2.07 μM and dynamic range of 2.07μM to 2.97 mM, thus indicating the tremendous potential of the materials in a wide range of electrobiocatalytic and bioelectronics applications.en_US
dc.identifier.urihttp://hdl.handle.net/10352/630
dc.language.isoenen_US
dc.publisherVaal University of Technologyen_US
dc.subjectSynthesisen_US
dc.subjectCharacterizationen_US
dc.subjectElectrocatalytic grapheneen_US
dc.subjectElectrochemical sensingen_US
dc.subjectBioelectronicsen_US
dc.subjectChemical vapour deposition (CVD)en_US
dc.subjectHeteroatom graphene (HGr)en_US
dc.subjectChronoamperometryen_US
dc.subjectGlucose oxidaseen_US
dc.subjectCarbonen_US
dc.subjectRaman spectroscopyen_US
dc.subject.lcshDissertations, Academic -- South Africa.en_US
dc.subject.lcshNanostructured materials.en_US
dc.subject.lcshChemistry -- Experiments.en_US
dc.subject.lcshCarbon nanotubes.en_US
dc.subject.lcshGraphene.en_US
dc.titleSynthesis and characterization of electrocatalytic graphene for electrochemical sensing and bioelectronicsen_US
dc.typeThesisen_US
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