Study On Reduction Of Graphene Oxide Via Ascorbic Acid And Its Capacitive Properties

Energy is an important issue of people’s survival,social progress and development of science and technology,and supercapacitor is taking an important part in the field of military,aviation,fuel,electric vehicles,hybrid electric vehicle applications because of its quick charge and discharge,wide working environment temperature,no pollution and no danger to the environment,long cycle life,high efficiency features.Carbon materials is the most widely applied in the super capacitor electrode materials.Since the advant of graphene as the new material,graphene was largely used in the energy storage element in a popular because of its elcellent electrical properties and lager specific surface and so on,especially in the supercapacitor.This artical was based on the nature flake graphite as raw material,using the oxidation-reduction method to prepare graphen by changing the pH value of graphene oxide,the dosage of reductant and the reaction temperture of reduction.This artical was to analyses reduction machanism of ascorbic acid and study the influnce of the different process parameters on the structure and electric properties of graphen by using XRD,FIR,SEM and sonstant current charge and discharge detection method.The result shows that the graphene oxide which has functional groups of-COOH、-OH、-C=O and-CH(O)CH-is reduced to graphene by ascorbic acid through the nucleophilic reaction.Ascorbic acid has a strong electron-withdrawing ability because of its five membered ring structure which makes it has a strong electron-withdrawing ability and stronger acid itself of carboxyl to have nucleophilic reactions with oxygen containing functional groups.And the ascorbic acid is oxidized to dehydrogenation ascorbic acid.The graphene samples have lamelarr structure,the diffraction peak of samples are between 24.317° and 25.503° which is corresponding to(002)diffraction peak of natural flake graphite and the layer spacing of about 0.349 to 0.366 nm.The best graphene sample was prapared from the graphene oxide which pH value is 9,and adding the reductant ascorbic acid by the ratio of 1:1 in the temperature of 80℃.It has characteristics of graphite layer structure which has slice layer and smooth surface.Its diffraction peak and layer spacing are 25.425° and 0.350 nm separately.Its first discharge capacity is 141.2 F/g,charging and discharging efficiency is 72.6% for the first time,and it keeps the discharge capacity of 87.7% after 200 cycles.