Kemijski pristup procesu dobivanja grafena i karakterizacija dobivenog produkta

undergraduate thesis

• Title (english): Chemical approach to the production of graphene and characterisation of obtained product
• Author: Vladimir Lukačević
• Mentor: Marijana Kraljić Roković (mentor)
• Committee member: Marijana Kraljić Roković (predsjednik povjerenstva)
• Committee member: Jozefina Katić (član povjerenstva)
• Committee member: Lidija Furač (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2015-09-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Tokom zadnje polovice prošlog desetljeća kemijski modificiran grafen proučavan je u
kontekstu mnogih primjena kao što su polimerni kompozitni materijali, premazi, boje,
biomedicinski materijali te niz drugih primjena radi svojih iznimnih električnih, mehaničkih,
toplinskih, te optičkih svojstava. Grafen je moguće sintetizirati primjenom različitih metoda
poput mehaničkog i elektrokemijskog raslojavanja grafita, kemijska sinteza iz otopine,
kemijskom depozicijom iz produkata niže molekulske mase te epitaksijalnim rastom na
površini silicij karbida. Kemijska priprava grafen oksida koji se dobiva iz grafita predstavlja
obećavajuću metodu za proizvodnju većih količina grafena.
Cilj ovog rada je bio sintetizirati grafen oksida (GO) iz uzorka prirodnog grafita
kemijskim putem koristeći Hofmannovu metodu. Oksidacijom grafita nastaje grafit oksid
koji se korištenjem ultrazvučne kupelji raslojava na grafen oksid. Kako bi se uklonile soli i
niskomolekularni ugljikovi spojevi otopina GO je dijalizirana te je potom provedena redukcija
GO u rGO pomoću natrij-bor hidrida.
Uzorci GO i rGO okarakterizirani su nizom metoda poput FT-IR spektroskopije,
termogravimetrijske analize (TGA), mikroskopa atomskih sila (AFM) te cikličke voltametrije.
FT-IR spektroskopijom je dokazano da GO sadrži kisikove funkcionalne skupine te da su u
procesu redukcije GO uklonjene hidroksi i epoksi skupine, a zaostale karbonilne skupine.
Korištenjem TGA analize određeno je da uzorak GO sadrži veći udio kisika u odnosu na rGO.
AFM metoda pokazala je da je da je GO raslojen do monosloja, a isto tako da je nakon
redukcije GO moguće izolirati monosloj rGO. Uzorak rGO nanesen je na elektrodu od
staklastog ugljika te su ispitana njegova kapacitivna svojstva metodom cikličke voltametrije.
Ispitivanje je provedeno u otopini 0,5 mol dm-3 Na2SO4. Pokazano je da uzorak posjeduje
dobra kapacitivna svojstva pri čemu su dobiveni specifični kapaciteti od 23 F g-1 do 7 F g-1 što
ovisi o uvjetima ispitivanja.

Abstract (english)

During the last decade, chemically modified graphene has been researched throughout
many applications such as polymer composite materials, coatings, paints, biomedical
materials and a number of other applications due to its exceptional electrical, mechanical,
termal and optical characteristics. Graphene can be prepared by different methods such as
mechanical and electrochemical exfoliation of graphite, wet chemical synthesis, chemical
vapour deposition and epitaxial growth of graphene. Chemical preparation of graphene oxide
obtained from graphite is a promising method for large-scale production of graphene.
The main goal of this paper was to prepare graphene oxide (GO) from natural graphite
by chemical oxidation using Hofmanns method. Chemical oxidation of graphite resulted in
graphite oxide that was exfoliated to GO by ultrasonication in deionised water. In order to
remove salts and low molecular products, the suspension of GO has been dialysed.
Reduction of GO to reduced graphene oxide (rGO) has been sucesfully cerried out using
sodium borohydride.
The samples of GO and rGO have been characterized by a number of methods such as
FT-IR spectroscopy, Atomic forse microscopy (AFM), termogravimetric analysis (TGA) and
cyclic voltammetry. By using FT- IR spectroscopy it has been shown that the GO contains
oxygen functional groups as well as that hydroxy and epoxy groups were removed in the
reduction process while carbonyl groups have remained. By using the thermogravimetric
analysis it has been determined that the sample of GO contains the greater share of oxygen
compared to rGO. AFM method has shown that the GO and rGO were completely exfoliatet.
The obtained rGO was applied on a glassy carbon support and examined by cyclic
voltammetry method. The experimen has been carried out in a 0,5 mol dm-3 of Na2SO4
solution. The specific capacitance value depended on testing procedure and it was foun to be
in the range from 23 F g-1 do 7 Fg-1.

• Keywords: AFM; ciklička voltametrija; grafen; grafen oksid; FT-IR; TGA
• Keywords (english): AFM; cyclic voltammetry; graphene; graphene oxide; FT-IR; TGA
• Language: croatian
• URN:NBN: urn:nbn:hr:149:894027
• Study programme: Title: Applied Chemistry - Undergraduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green technologies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2016-11-18 14:05:06