Influence of surfactant structure on electrochemical exfoliation of graphite

Autor: Ivić, Kristina
Přispěvatelé: Kraljić Roković, Marijana
Jazyk: chorvatština
Rok vydání: 2016
Předmět:
Popis: Zadatak ovog rada bio je provesti elektrokemijsko raslojavanje prirodnog grafita s ciljem dobivanja grafenske strukture. Kao elektroliti korištene su 0,1 mol dm^-3 vodene otopine natrijevog dodecil benzen sulfonata (SDBS) i natrijevog dodecil sulfata (SDS). Polarizacija je provedena naizmjence kod pozitivnih i negativnih potencijala korištenjem dvoelektrodnog sustava pri naponima od 2,5 V, 2,8 V, 3,0 V i 3,2 V gdje je grafitna elektroda spojena kao anoda te pri naponu od 2,8 V gdje je grafitna elektroda spojena kao katoda. Polarizacijom grafita u području pozitivnih potencijala SDS i SDBS se interkaliraju u strukturu grafita. Uz to pri pozitivnim potencijalima može doći do oksidacije ugljika i reakcije razvijanja kisika. Primjenom negativnih potencijala dolazi do interkalacije kationa u strukturu grafita te do reakcije razvijanja vodika. Karakterizacija elektroda je provedena korištenjem cikličke voltametrije i bilježenjem strujnih tranzijenata tijekom polarizacije, a produkti dobiveni raslojavanjem su okarakterizirani UV/Vis spektroskopijom i mikroskopom atomskih sila (AFM). Cikličkom voltametrijom je dokazano da je tijekom polarizacije došlo do ekspanzije elektrode na što su ukazali i strujni tranzijenti zabilježeni tijekom samog procesa. Da je došlo do raslojavanja grafita nakon polarizacije može se uočiti po promjeni boje otopine elektrolita koja postaje smeđa. Metodom UV/Vis spektrofotometrije je dokazano prisustvo grafenova oksida u otopini, a mikroskopom atomskih sila je dokazano da su uzorci, ovisno o otopini i vrsti elektrode, raslojeni do monosloja ili do listova koji se sastoje od dva do tri grafenska sloja. The aim of this work was to perform electrochemical exfoliation of natural graphite in order to obtain graphene. In this process 0,1 mol dm^-3 sodium dodecylbenzene sulfonate (SDBS) and 0,1 mol dm^-3 sodium dodecyl sulfate (SDS) were used as supporting electrolytes. Graphite electrode was alternately polarised at positive and negative potentials by using two electrode system and by applying voltage 2,5 V, 2,8 V, 3,0 V or 3,2 V when graphite electrode was used as anode. When graphite electrode was used as cathode the voltage of 2,8 V was applied. During positive polarisation SDS and SDBS are intercalated within the structure of graphite. Furthermore, during positive polarisation oxygen evolution as well as carbon oxidation takes place. By applying negative potential cations are intercalated into graphite working electrode and also hydrogen evolution takes place. Electrodes were characterized by using cyclic voltammetry and by analysing the current transients registered during the polarization. The exfoliated products were characterized by employing UV/Vis spectrophotometry and atomic force microscopy (AFM). By using cyclic voltammetry and by monitoring current transients it was shown that during polarization process the electrode was expanded The brown colour of the electrolyte indicates that the graphite was exfoliated and UV/Vis spectra of graphene/SDS suspensions has proved that obtained product was graphene oxide. Atomic force microscopy has shown that depending on the type of electrolyte and electrode, monolayer or bi- and trilayer graphene was present within the solution.
Databáze: OpenAIRE
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