Priprava kompozita metalni oksid/grafen i njegova primjena u superkondenzatorima

master's thesis

• Title (english): Preparation of metal oxide/graphene composite and its application as active electrode material in supercapacitors
• Author: Magdalena Kralj
• Mentor: Marijana Kraljić Roković (mentor)
• Committee member: Marijana Kraljić Roković (predsjednik povjerenstva)
• Committee member: Zoran Mandić (član povjerenstva)
• Committee member: Tatjana Gazivoda Kraljević (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Svrha ovog rada bila je priprema i karakterizacija kompozitnog materijala grafen/SnO2 hidrotermalnom sintezom potpomognutom mikrovalovima i klasičnom hidrotermalnom sintezom. Jedan od ciljeva ovog rada ujedno je bio i priprava i karakterizacija superkondenzatora koji se temelje na grafen/SnO2 aktivnim materijalima. Tijekom hidrotermalne metode potpomognute mikrovalovima produkt je dobiven u obliku suspendiranih čestica. dok je tijekom klasične hidrotermalne sinteze dobiven hidrogel. Kapacitivna svojstva uzoraka sintetiziranih u mikrovalnom reaktoru ispitana su korištenjem metode cikličke voltametrije i elektrokemijske impedancijske spektroskopije pri čemu je dokazano da KOMPOZIT 1, KOMPOZIT 2 i KOMPOZIT 3 karakteriziraju odlična kapacitivna svojstva. uz dobivene vrijednosti specifičnog kapaciteta od 3,51 do 91,94 Fg^-1. Kao najbolji pristup sintezi pokazao se postupak kojim je dobiven KOMPOZIT 2 stoga je navedeni pristup korišten tijekom hidrotermalne sinteze. U hidrotermalnoj sintezi su dobivena tri različita kompozita u obliku hidrogela (KOMPOZIT 21, KOMPOZIT 22 i KOMPOZIT 23) te su iz navedenih hidrogelova direktno priređeni superkondenzatori (Superkondenzator 1, Superkondenzator 3, Superkondenzator 2). Najbolja svojstva je pokazao Superkondenzator 3 kod kojeg je zabilježen specifični kapacitet od 55,92 F g^-1 te specifičnu energiju od 71,58 Ws g^-1. Uvid u morfologiju i sastav uzoraka dobiven je SEM snimkama koje pokazuju da je za KOMPOZIT 2 dobiven najveći udio SnO2 te da je sloj najhomogeniji. Kod hidrogelova je dokazana porozna struktura koja osigurava visoke kapacitete. XPS analizom uzoraka potvrđeno je da je došlo do redukcije grafenova oksida (GO) u grafen (rGO) i oksidacije Sn2+ u Sn4+. FTIR spektroskopijom dokazano je prisustvo određenih kisikovih funkcionalnih skupina kao i prisustvo –Sn-O- veze. Provedbom rendgenske difrakcije vidljivi su i karakteristični maksimumi koji odgovaraju strukturi SnO2. Navedene metode su dokazale da je tijekom sinteze doista došlo do formiranja kompozitnog materijala grafen/SnO2.

Abstract (english)

The main purpose of this theses was the preparation and characterization of the composite material graphene/SnO2 using microwave-assisted hydrothermal synthesis and convencional hydrothermal synthesis. One of the aims of these theses was also the preparation and characterization of supercapacitors based on graphene/SnO2 active materials. The suspended particels were obtained using microwave-assisted hydrothermal synthesis, while hydrogel was obtained using classical hydrothermal synthesis. The capacitive properties of the samples prepared by microwave assisted method were examine using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which proven excellent capacitive properties of COMPOSITE 1, COMPOSITE 2 and COMPOSITE 3 were specific capacity values 3.51 - 91.94 Fg^-1 were obtained. The process of obtaining COMPOSITE 2 shown to be the best approach for synthesis and therefore it has been used during hydrothermal synthesis. In the hydrothermal synthesis three different composites were obtained in the form of hydrogels (COMPOSITE 21, COMPOSITE 22 and COMPOSITE 23) and supercapacitors (Supercapacitor 1, Supercapacitor 3 and Supercapacitor 2) were directly prepared by using these hydrogels. Supercapacitor 3 has shown the best properties were specific capacitance, 55.92 Fg^-1 and specific energy, 71.58 Ws g^-1 were recorded. Insight into morphology and composition of the materials was obtain by SEM technique showing that COMPOSITE 2 is the most homogeneous material, with the largest amount of SnO2. The porous structure is determine for hydrogels that provides high capacitance values. XPS analysis of the samples comfirmed reduction of graphene oxide (GO) to graphene (rGO) and oxidation Sn2+ in Sn4+. FTIR spectroscopy showed the presence of oxygen functional groups, as well as the presence of a –Sn-O- bonding. Using X-ray diffraction, the characteristic maximums corresponding to the SnO2 structure are visible. The methods used in this work have confirmed that graphene/SnO2 composite was obtained.

• Keywords: ciklička voltametrija; grafen; hidrogel; hidrotermalna sinteza; kompozitni materijal; SnO2; specifični kapacitet; superkondenzator
• Keywords (english): cyclic voltammetry; graphene; hydrogel; hydrothermal synthesis; composite material; SnO2; specific capacitance; supercapacitor
• Language: croatian
• URN:NBN: urn:nbn:hr:149:072117
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-04-22 14:20:11