Preparation and characterization of silica, reduced graphene oxide and composite aerogels

Abstract

Ph. D. Thesis.In this thesis, experimental results are reported on the synthesized of waterglass-based silica aerogels monoliths by mixing graphene oxide. The new ambient pressure approach is used to produce aerogels by using a mixture of sodium bicarbonate and water instead of low surface tension solvent. Furthermore, to enhance mechanical properties graphene oxide as nanofillers is added into silica matrix to synthesize composite aerogels based on sol-gel technology. Furthermore, we report a simple method for obtaining reduced graphene oxide aerogels doped with different metal oxide nanoparticles, germanium dioxide (GeO2), cobalt ferrite (CoFe2O4), and iron(III) oxide (Fe3O4) by using supercritical drying method. Firstly, all metal oxide nanoparticles are synthesized. Then metal oxide nanoparticles are added into graphene oxide solution and sodium bisulfide is utilised as a cheap reducing agent. Lastly, prepared aerogels’ properties such as surface area, morphology, the chemical composition, and electrochemical measurements as an anode material for lithium-ion batteries are investigated. Finally, ambient pressure dried graphene-based aerogels are produced with common devices by rewording a partially reduced graphene oxide hydrogel with an ice-template method. This work can be cost effective of high-performance graphene aerogels. Scanning electron microscope (SEM), X-ray diffraction (XRD), uniaxial compression test, fourier transform infrared spectroscopy (FTIR), raman spectroscopy, Brunauer - Emmett - Teller (BET) theory and Barret - Joyner - Halenda (BJH) method are utilised to characterise the produced aerogels.Turkish Governmen