Title Modifikacija grafenova oksida aromatskim aminima Title (english) Modification of graphene oxide with aromatic amines Author Ivan Spajić Mentor Zoran Mandić (mentor)Committee member Zoran Mandić (predsjednik povjerenstva)Committee member Suzana Sopčić (član povjerenstva)Committee member Stjepan Milardović (član povjerenstva)Granter University of Zagreb Defense date and country 2017-07-11, Croatia Scientific / art field, TECHNICAL SCIENCES Abstract U ovom radu provedena je modifikacija grafenova oksida (GO) aromatskima aminima, anilinom i o-fenilendiaminom, s ciljem dobivanja GO-elektroda poboljšanih kapacitivnih svojstava. Sinteza GO-a provedena je iz grafita prema Hofmann-ovoj metodi, te je dobiveni GO nanešen na zlatom prevučenu kvarcnu elektrodu metodom spin coatinga. Tanki sloj GO-a modificiran je u različitim sustavima otopina anilina i o-PDA na način da su GO-elektrode uranjane u otopine tijekom 24 sata (inkubacija). Za inkubaciju su pripravljene 4 vrste otopina, 0,1 M otopina anilina i 0,1 M otopina o-PDA svaka u H2O:CH3OH i H2SO4 otopinama. Ispitivanja modificiranih GO-elektroda provedena su metodom cikličke voltametrije i pomoću elektrokemijske kvarc-kristalne mikrovage (EQCM). Za karakterizaciju dobivenih GO-elektroda korištena je FTIR-ATR spektroskopija.
Modifikacijom GO-a u otopinama anilina i naknadnom elektrokemijskom oksidacijom (do 0,8 V vs. ZKE) poboljšan je kapacitet GO-a, međutim puno veće poboljšanje kapaciteta postignuto je modifikacijom u otopinama o-PDA. Specifični kapacitet pripravljenog GO-a je vrlo nizak i iznosi oko 5 F/g, a nakon modifikacije GO-elektroda u H2O:CH3OH otopini anilina i nakon elektrokemijske oksidacije postignut je za oko 3 puta veći specifični kapacitet. U slučaju modifikacije u H2SO4 otopini anilina dolazi do značajnog povećanja kapaciteta GO-a, ali nakon elektrokemijske oksidacije dolazi do naglog pada, vjerojatno zbog nastajanja nevodljivog oblika polianilina. Međutim, modifikacijom GO-a u H2O:CH3OH otopini o-PDA dolazi do vezanja dovoljnih količina monomera za formiranje polimernih lanaca fenazenske strukture, što povisuje specifični kapacitet GO-a na 113,6 F/g. Modifikacijom GO-a u H2SO4 otopini o-PDA, također dolazi do povećanja specifičnog kapaciteta, koji iznosi 83,4 F/g, opet zahvaljujući polimernim lancima o-PDA. Obje GO-elektrode modificirane u otopinama o-PDA pokazuju izvrsnu stabilnost i zadržavaju relativno visoke kapacitete i nakon elektrokemijske oksidacije. Prema tome, GO modificiran molekulama o-PDA pokazuje vrlo dobra elektrokemijska svojstva, dobru vodljivost električne struje, te obećavajuće rezultate za primjenu ovakvih elektroda u superkondenzatorima.
Abstract (english) 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.
Keywords
grafenov oksid (GO)
anilin
o-fenilendiamin (o-PDA)
vodljivi polimeri
superkondenzator
Keywords (english)
graphene oxide (GO)
aniline
o-phenylenediamine (o-PDA)
conducting polymers
supercapacitor
Language croatian URN:NBN urn:nbn:hr:149:526510 Study programme Title: Materials Science and Engineering - Graduate study Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2019-11-11 12:05:20
