Study On Electrochemical Sensing Of Graphene Nanocomposites

Graphene exhibits excellent electronic, optical, thermal and mechanical peroperties owing to its unique two-dimensional nanostructure. Recently, graphene has shown promising applications in photoelectronic materials, energy materials and bio-materials. Nanoelectroanalytical chemistry is an attracting interdisciplinary field, which combines characteristics of electrochemistry (e.g., simplicity, speed, high selectivity and high sensitivity) with unique properties of nanomaterials (e.g., electronic, optical, magnetic and catalytic). Graphene has shown excellent performance in nanoelectroanalytical chemistry that it not only could act as an advanced support with very large surface area for immobilizing different targets, but also effectively promote the electron transfer between electrode and analytes. Graphene-based nanocomposite is nano-assembled systems that composed by graphene with metal, metal oxide and polymer at nanoscale, which exhibit synergetic properties and enchaced performance. In this thesis, we studied the preparation and electrochemical properties of graphene nanocomposites including graphene-TiO2and graphene-polyaniline. Their applications in electrochemical sensors have been investigated. The research works are summarized as follows:1. The graphene-TiO2nanocomposite was prepared through hydrothermal reaction by using graphene oxide and titanium(IV) isopropoxide as starting materials. TiT2nanoparticles were in situ crystallized and deposited on graphene surfaces. The as-prepared graphene-TiO2nanocomposite modified glassy carbon electrode exhibit enhanced amperometric response to L-tryptophane and L-tyrosine. The detection limits of0.7and2.3μM, and sensitivity of75.9and22.8μA mM-1for L-tryptophane and L-tyrosine were obtained on the modified electrodes, respectively.2. The electrochemical behavior of paracetamol on the as-prepared graphene—TiO2nanocomposite modified glassy carbon electrode was investigated. This electrode material exhibits good adsorptivity to analyte with surface concentration of3.24×10-9 mol cm-2. The electrochemical sensor exhibits favorable electrochemical sensing performance to paracetamol, with detection limit of2.1×10-7M and linear range of1-100μM.3. The graphene-polyaniline nanocomposite was prepared by in situ polymerization. The electrochemical property of the nanocomposite and the electrochemical behavior of4-aminophenol on the modified electrode was investigated. The as-prepared nanocomposite has good electron transfer capability and enhanced adsorpbility to analyte. This electrode material exhibits favorable amperometric response to4-aminophenol with detection limit of6.5×10-8M and sensitivity of604.2μA mM-1.