Synthesis Of Hierarchical Nanocomposites Of Graphene And Its Electrochemical Applications

Nanomaterials which provide excellent catalytic performance, large specific surface area, strong adsorption performance, good biological compatibility and electron transfer ability has high promising applications in electrochemical sensors, electrochemical energy storage and electrochemical catalytic. While the rapid development of nanotechnology, put forward higher requirements on the performance of nanomaterials. Nanomaterials with simple structure and single performance can not able to meet these needs. Graphene has become a rising start due to its unique optical and electronic properties. In this paper, hierarchical nanocomposite of graphene, polyaniline and inorganic nanoparticles were constructed based on chemical modification of graphene. These nanocomposites can not only keeping the inherent properties of graphene, polyaniline and inorganic nanoparticles, but also can produce novel synergistic effect. With the high catalytic performance and high charge storage properties, they can be used in supercapacitor, electrochemical sensor. The main contents and results are as follows:(1) This work presents an electrochemical approach for the detection of H2O2based on Prussian blue (PB) nanocubes-nitrobenzene-reduced graphene oxide (RGO) nanocomposites (PB nanocubes-nitrobenzene-RGO). The hybrid nanocomposites were constructed by growing PB nanocubes onto the nitrobenzene-RGO composites which were prepared by spontaneous grafting nitrophenyl groups to the basal carbon atoms of RGO based on chemical bonding. The obtained PB nanocubes-nitrobenzene-RGO nanocomposites were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The sensor shows good electrocatalysis toward the reduction of H2O2. The resulted H2O2biosensor exhibited a rapid response of2s, a low detection limit of0.4μM, a wide linear range of1.2μM-15.25mM (γ=0.999) and high sensitivity of300.16μA cm-2mM-1, as well as good stability, repeatability and selectivity. The sensors might be used as a promising one for practical application.(2) We put forward a new synthetic route to synthesize a hierarchical nanocomposite (PANI-frGO) of polyaniline (PANI) nanowire arrays covalently bonded on reduced graphene oxide (rGO). In this strategy, nitrophenyl groups were initially grafted on rGO via C-C bond, and further reduced to aminophenyl to act as anchor sites for the growth of PANI arrays on rGO. The functionalized process was confirmed by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The electrochemical properties of the PANI-frGO as supercapacitor materials were investigated. The PANI-frGO nanocomposites showed high capacitance of590F g-1at0.1A g-1and had no loss of capacitance after200cycles at2A g-1. The improved electrochemical performance suggests promising application of the PANI-frGO nanocomposites in high-performance supercapacitors.(3) In this part, the nanocomposites of polyaniline (PANI) nanowire arrays on reduced graphene oxide sheets (rGO) immobilized with CO3O4was synthesized and characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The electrocatalytic oxidation and detection of cysteine or N-acetyl cysteine based on composite modified glassy carbon electrodes were investigated by cyclic voltammetry, amperometry, double potential step chronoamperometry and amperometric responses. The modified electrode showed good electrocatalytic oxidation to these two amino acids.