Dye Functionalization And Modification Of Polyaniline/graphene Composites

Polyaniline/graphene composites are considered as a kind of ideal supercapacitor electrode materials because of the high theory specific capacitance and excellent conductivity of polyaniline(PANI)and high specific surface area of graphene.However,the dispersibility and solubility of graphene is poor because of the strong π-π*interaction and the absence of functional groups on graphene nanosheets.Hence,graphene easily aggregates and polyaniline monomers easily homopolymerize during the preparation process of polyaniline/graphene composites.Therefore,more attentions are given to exploring functional and modified graphene-based composites.The details of this thesis are as follows:Firstly,carbon nanohorns decorated graphene oxide/polyaniline(CGOP)composites were prepared in the presence of graphene oxide(GO).Carbon nanohorns(CNHs),serving as spacers,were introduced into the CGOP composite to prevent GO agglomeration.Graphene nanosheets in the CGP composite containing 5 wt.%CNHs,i.e.CGOP5,exhibited a uniform nanostructure without agglomeration because of the isolation effect of CNHs and PANI.Then,the CGP5 composite was obtained by reducing the CGOP5 composite using hydrazine hydrate.The specific capacitance of CGP5 was up to 769 F/g at a current density of 1 A/g.Importantly,CGP5 possessed a good rate capability;and the specific capacitance was 631 F/g at a current density of 10 A/g.Furthermore,an asymmetric electrode system was assembled and investigated using a two-electrode system with CGP5 and its carbonized nanocomposite(C-CGP5)as the positive and negative electrodes,respectively.The energy density of 51.6 kW/kg was achieved at a power density of 1100 W/kg,and an 88%capacitance retention rate after 2000 cycles at a scanning rate of 100 mV/s was obtained.Tetraphenylporphyrin tetrasulfonic acid(TPPs)functional graphene oxied/polyaniline nanocomposites(PGOT)were prepared via in an situ chemical oxidative polymerization.GO contained in PGOT was reducted by hydrazine hydrate and PGOT became PGT.The results shows that GO has no aggregation and PANI covers on GO uniformly when the TPPs content reached to 4 wt.%(PGOT4).The maximum specific capacitance reached up to 493 F/g at a current density of 1 A/g in 1 M H2SO4 electrolyte.The specific capacitance of PGT4 was up to 685 F/g at a current density of 1 A/g.what’s more,it’s specific capacitance almost kept 100%after 2000 cycles at a scan rate of 100 mV/s.It’s suggesting that PGT4 is wonderful as an electrode material for supercapacitor.Whereafter,K3[Fe(CN)6]and K4[Fe(CN)6]were added into 1 M H2SO4,and the specific capacitance of PGT4 was improved greatly.At a current density of 10 A/g,the specific capacitance came up to 4350 F/g,and the capacitance rentention rate was 85%after 2000 cycles at a scan rate of 100 mV/s.