Modifikacija grafenova oksida aromatskim aminima

In this work, modification of graphene oxide (GO) with aromatic amines, aniline and o-phenylenediamine, has been carried out with the aim of obtaining GO-electrodes with improved capacitive properties. The synthesis of GO was performed from graphite according to Hofmann's method and the resulting GO was deposited on a gold covered quartz crystal electrode by the spin coating method. Thin layer of GO was modified in various solutions of aniline and o-PDA by inserting GO-electrodes into solution for 24 h (incubation). Four types of solutions were prepared for incubation: 0.1 molar solutions of aniline and o-PDA in H2O:CH3OH and H2SO4. Modified GO-electrodes were tested by cyclic voltammetry method and using quartz crystal microbalance (EQCM). FTIR-ATR spectroscopy was used for characterization of the obtained GO electrodes. Modification of GO in aniline solutions and his subsequent electrochemical oxidation (up to 0.8 V vs. SCE) improved the capacitance of GO, but modification of GO in o-PDA solutions resulted in much greater capacitance enhancement. The specific capacitance of the prepared GO is very low, about 5 F/g, but after modification of GO in aniline solution of H2O:CH3OH and after his electrochemical oxidation, specific capacitance increased about 3 times. In the case of modification GO in aniline solution of H2SO4 a significant increase in its capacity was obtained, but after electrochemical oxidation of GO a sudden fall in capacitance occured, probably due to the emergence of a non-conducting form of polyaniline. However, by modifying GO in o-PDA solution of H2O:CH3OH, sufficient amount of monomer was attached to GO to form the polymer chains of the phenazine structure, which increases a specific capacitance of GO to 113,6 F/g. GO modified in o-PDA solution of H2SO4, also gives an increase in specific capacity which is 83.4 F/g, again due to the polymeric chains of o-PDA. Both GO-electrodes modified in o-PDA solutions showed excellent stability and retained relatively high capacitances after electrochemical oxidation. Thus, GO modified with o-PDA molecules showed excellent electrochemical properties, good electrical conductivity and promising results for its application in supercapacitors.