Preparation Of Graphene Modified Electrode Materials And Their Applications

Graphene, a two-dimensional new carbon material with single atomic layer, has many unique physical and chemical properties. Since its inception in 2004, graphene has attracted great attention for both fundamental science and applied research. The theory surface area of a single graphene is up to 2630 m2 g-1 and its conductivity is very good, so graphene has great potential in the nano-composite materials field and it is also the hot research in the analyticalchemistry field. The main results were given as follows: 1. Graphite oxide (GO) was prepared from graphite power by Hummers'liquid oxidation method. The graphene nanosheets supporting Pd catalysts were prepared by a one-step chemical reduction method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) neasurements were used to characterize the particle size and crystallinity of the catalysts. The Pd nanoparticles were well dispersed on the surface of the graphene nanosheets with particle sizes of 3-5 nm. The electrocatalytic oxidation of ethanol was studied by electrochemically active surface area (ECSA), cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP) measurements. It was found that the Pd/graphene composites had better catalytic activity than the Pd/Vulcan XC-72 catalysts toward ethanol oxidation in alkaline media.2. Tin oxide (SnO2)/graphene nanosheets (GNS) composite was prepared by a simple chemical-solution method. Then Pd/SnO2-GNS catalysts were synthesized by a microwave-assisted reduction process. The content of SnO2 in the Pd/SnO2-GNS catalysts was discussed, and the as-synthesized samples were characterized by using XRD, TEM and energy-dispersive spectroscopy (EDS) techniques. The electrocatalytic performances of Pd/SnO2-GNS catalysts for ethanol oxidation were studied by cyclic voltammetric. It was found that compared with Pd/GNS, the Pd/SnO2-GNS catalyst showed superior electrocatalytic activity for ethanol oxidation when the mass ratio of SnCl2·2H2O precursor salt to graphite oxide was about 1:2.3. The graphene was prepared by reduction of GO with hydrazine hydrate, then the Pt/graphene modified electrode was prepared by electrochemical deposition of Pt on the surface of graphene. TEM results show that the Pt nanoparticles were successfully deposited on the surface of graphene with fioc agglomeration and the particles size were between 10-20 nm. Cyclic voltammetry was used to study the electrochemical behavior of Pt/graphene modified electrode towards methanol. It was found that the Pt/graphene modified electrode had better catalytic activity than the Pt/MWCNT modified electrode toward methanol oxidation. While optimizing the experimental conditions a new method of determination of methanol based on the voltammetric analysis was established. In the range of 2.5-32.5 mmol L-1, the peak current was linearly proportional to the concentration of methanol. The detection limit was estimated to be 89μmol L-1.