Functionalization Of Graphene With Polymer And Its Application In Fabrication Electrochemical Sensor

Graphene is a one-atom-thick planar sheet of sp²-bonded carbon atoms denselypacked in a honeycomb crystal lattice. The unique features of grapheme have attractedtremendous interest both in academics and industry. Since its discovery in2004,graphene has demonstrated numerous applications in nanoelectronics, biosensors,drug delivery, supercapacitors, fuel cells, transistors, and nanocomposites due to itsexcellent electrical conductivity, a high specific surface area, excellent chemicalresistance and mechanical flexibility. However, in some cases, the use of puregraphene is problematic due to its inherent shortcomings, such as poor dispersivity ina hydrophilic or hydrophobic media as well as in the polymer matrix, irreversibleagglomerates or even restack and the absence of a band gap in pristine grapheme. Allthese problems could be alleviated through the modification of grapheme. Therefore,functionalization of grapheme is significant work. The chemical functionalization ofgraphene is a particularly attractive target because it can improve the solubility andprocessability as well as enhance the interactions with organic polymers.In the present study, graphene/Au hybrid nanostructures were synthesized usingwater-soluble functional polymer of polyvinyl pyrrolidone covalently functionalizedgraphene oxide （PGO） and HAuCl₄as template and precursor, respectively. Theobtained graphene/Au hybrid nanostructures were then applied to modify the GCE tofabricate the electrochemical sensor for L-CySH. The modified electrodedemonstrated enhanced electronic properties due to its combination of the excellentelectronic conductivity properties of graphene and electronic catalytic activity of Aunanoparticles. The specific research content is summarized as follows:（1） Synthesis of azide-terminated polyvinyl pyrrolidone polymer （PVP-N₃）.Azide group terminated polyvinyl pyrrolidone （PVP-N₃） was synthesized byreversible addition-fragmentation chain transfer polymerization （RAFT）. Thestructure of polymer was characterized by FTIR and1HNMR.（2） Synthesized of PVP covalently functionalized graphene oxide （PGO）. Thealkyne-functionalized GO （AGO） was firstly synthesized by the nucleophilicsubstitution reaction between amine groups of propargylamine and epoxide groups ofGO in alkaline media. And then, PVP was grafted on the surface of GO through the [3+2] Huisgen cycloaddition between the alkyne of AGO and azide groups of PVP-N₃using CuBr/PMDETA complex as the catalyst, leading to the formation of PGO. The structure of formed PGO was characterized with FTIR, Roman, XPS and TGAanalysis.（3） Synthesis of graphene/Au hybrid nanosheets and its electrochemicalsensor for L-CySH. The graphene/Au hybrid nanosheets were synthesized usingPGO, HAuCl₄and NaBH₄as template, precursor and reduction agent, respectively.The obtained graphene/Au hybrid nanosheets were further utilized to modify GCE tofabricate the L-CySH sensor. The electrochemical behaviour of L-CySH on solidelectrodes were studied with cyclic voltammetry and chronoamperometry. Also, theeffects of pH and scanning rate on electrochemical behaviour of L-CySH were alsoinvestigated.