Electrochemical Properties Of Graphene Modified Electrode

Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice, which can be considered as a basic building block for other kinds of carbon-based materials including 0D fullerenes, 1D carbon nanotubes and 3D graphite, with outstanding and unique physical, chemical and mechanical properties, and has extensive applications in the design of devices of micro-nano-electronices, optoelectronics, novel composite materials and sensing materials. The related researches based on graphene have been becoming one of a hotspot in the field of electrochemistry. This thesis focuses on the different graphene modified electrode condition and electrochemical basic research, some related electrochemical properties of graphene and graphene-based composite materials were carried out. The main points of this thesis can be briefly summarized as follows:(1) Interconnect graphene with well conductive polyaniline (PANI), and research the electrochemical properties of the graphene/PANI composite. Cyclic voltammetry (CV) demonstrates that PANI is electroactive in the neutral and alkaline media after interconnected with graphene and gives the conceivable evidence for electroactivity of the nanocomposite: the charge-transfer interaction. FT-IR, Raman and UV-vis spectroscopy were used for characterization the interconnection between PANI and graphene. The electroactive of the graphene/PANI nanocomposite in the neutral media is envisaged to substantially enable it very useful for the development of electrochemical sensors or biosensors. And also, the electroactive of the graphene/PANI nanocomposite in all kinds of solution made it useful in the field of pH sensor.(2) Confine graphene onto electrode surface by simply using Vaseline as the insulting matrix, and research the electrochemical properties of the graphene/Vaseline film electrodes. CV studies reveal that a large amount of graphene (typically, 10.0μg/mL) leads to the formation of the film electrodes with a conventional dimension, while a small amount of graphene (typically, 1.0μg/mL) essentially yields the graphene film electrodes like a nanoelectrode ensemble. At the same time, the as-prepared graphene film electrodes have a good electrochemical activity as well as a high stability. As a new kind of carbon-based film electrodes, the graphene film electrodes are believed to be potentially useful for fundamental electrochemical studies and for practical applications.(3) Controllable adsorption of graphene nanosheets onto the self-assembled monolayer (SAM) of alkanethiol at Au electrodes, and research of the electrochemical properties of the graphene/alkanethiol SAM-modified electrodes. Nyquist plots show a gradual decrease of the charge transfer resistance of the [Fe(CN)6]3-/4- redox couple at the graphene/SAM electrode with prolonging the self-assembly time, suggesting the controllable adsorption of graphene nanosheets onto the SAM. CV studies reveal that the graphene/SAM electrodes have tunable dimensions ranging from a nanoelectrode ensemble to a conventional electrode, depending on the self-assembly time of graphene nanosheets. The excellent electrocatalytic activity and anti-interference performance of the graphene/SAM electrode toward ascorbic acid, dopamine and uric acid was also given in this paper. At the same time, in order to explore the possible experimental mechanism, we envisage two mainly possible reasons for electron transfer and the relevant influential factors of the electrochemical double layer formed on the graphene/alkanethiol SAM-modified electrodes. The results show that the electron-transfer rate at the graphene/SAM modified electrodes decayed with the length of carbon chain of SAM, and the electron-transfer rate of different carbon-based material is that graphene is greater than meso carbon, and graphite is the worst. These demonstrations offer a facile approach to fabrication of stable graphene based film electrodes with excellent electrochemical properties that are believed to be particularly useful for fundamental studies on carbon-based electrochemistry and for practical electrochemical applications.