Controlled Synthesis And Modification Of Graphene Network Materials And The Effect On The Supercapacitor Performance

Graphene with one-carbon-atom thick and two dimensional layer structure has exhibited excellent theoretical conductivity,high specific surface area and stable chemical property.However,during the preparation process of graphene by the chemical oxidation and reduction method,defects were remained on the graphene layers and the?-?effect between the graphene sheets caused agglomeration of graphene layers,which resulted in unsatisfied pratical performance of graphene materials.Therefore,here we aimed to improve the electrical property and solve the agglomeration problem of graphene materials.Firstly,platinum and palladium nanoparticles were used to improve the electrical and catalytic property of the graphene materials,respectively.Secondly,the carbonaceous of the bean dregs were introduced between the graphene sheets and acted as inter-layer spacers to prevent the agglomeration of graphene sheets.Furthermore,the carbonaceous of the bean dregs can also bring the N element to the carbon composites,which can improve the capacitance performance of the carbon composite material.The detailed content are illustrated as follows:?1?The preparation and characterization of Pt/graphene/carbon materials.Pt nanoparticles was in-situ decorated on the graphene sheet by microwave irradiation of the mixture of graphene oxide and H₂PtCl₆·6H₂O.Then the Pt/graphene materials were prepared by hydrothermal treatment and high temperature annealing.The study found that introduction of Pt nanoparticles into the graphene can largely reduce the voltage drop and effective series resistance and increase the power density of the supercapacitors.The power density of optimized Pt/graphene carbon composites is 9.5 times higher,which is 7.1 KW Kg^-1,than the carbon composite without Pt decorating under the current density of 1A g^-1.?2?The preparation and characterization of Pd/graphene materials.The microwaved products of Pd/graphene were prepared by microwave irradiation of the mixture of graphene oxide and K₂PdCl₆.Based on the microwave products of Pd/graphene,the Pd/graphene materials were prepared,following by hydrothermal treatment and high temperature annealing.The morphology and phase structure of Pd/graphene materials were characterized through XRD,FE-SEM and Raman et al.The result shows that the Pd nanoparticles can also reduce the equivalent series resistance,voltage drop and increase the power density of supercapacitor.But the effect of Pd nanoparticales on the equivalent series resistance,voltage drop and the power density is much lower than that when using Pt nanoparticles to modify the graphene electrode.?3?The preparation and characterization of graphene oxide and bean dregs derived.The carbon composites materials were prepared by hydrothermal treatment and high temperature annealing of the mixed graphene oxide and bean dregs precursors.The result shows that the electrochemical performance of the optimized composite carbon material was greatly improved.And the specific capacitance of the optimized composite carbon material was201.9 F g^-1,which was much higher than pure carbonized bean dregs(78 F g^-1)and pure graphene(93 F g^-1),at the current density of 1 A g^-1.