Synthesis of Multifunctional One-dimensional and Two-dimensional Highly Conductive Nanomaterials for Charge Storage Applications

Shayesteh-Zeraati, Ali

Synthesis of Multifunctional One-dimensional and Two-dimensional Highly Conductive Nanomaterials for Charge Storage Applications

dc.contributor.advisor	Sundararaj, Uttandaraman
dc.contributor.author	Shayesteh-Zeraati, Ali
dc.contributor.committeemember	Roberts, Edward P.L.
dc.contributor.committeemember	Kim, Seonghwan
dc.contributor.committeemember	Shimizu, George K.H.
dc.contributor.committeemember	Cakmak, Mukerrem
dc.date	2020-02
dc.date.accessioned	2020-01-30T16:51:52Z
dc.date.available	2020-01-30T16:51:52Z
dc.date.issued	2020-01
dc.description.abstract	In this thesis, highly conductive 1D and 2D nanomaterials including silver nanowire (AgNW), graphene, and MXene were synthesized and used for charge storage. AgNW with high purity and aspect ratio was incorporated in poly(methyl methacrylate) (PMMA) to fabricate a high performance dielectric material. To improve the dielectric performance of the nanocomposites, a hybrid structure, containing AgNW and MnO2NW, was utilized to not only enhance the dielectric constant but also minimize the dielectric loss. The fabricated AgNW:MnO2NW (2.0:1.0 vol %) hybrid nanocomposite showed a high dielectric constant (64 at 8.2 GHz) and low dielectric loss (0.31 at 8.2 GHz), which were among the best reported values in the literature in the X-band frequency range (8.2–12.4 GHz). This superior dielectric performance of the hybrid nanocomposites was attributed to (i) dimensionality match between the nanofillers, (ii) better dispersion state of AgNW in the presence of MnO2NW, (iii) positioning of ferroelectric MnO2NW in between AgNWs, (iv) barrier role of MnO2NW, and (v) the aligned structure of AgNWs, as nanoelectrodes. In the second phase of this thesis, graphene was synthesized via electrochemical exfoliation of graphite in different inorganic salt electrolytes. Electrochemically exfoliated graphene (EEG) sheets synthesized in this thesis had a good dispersibility in water as well as a high electrical conductivity. This eliminated extra steps to increase conductivity such as reduction of graphene oxide. By utilizing these advantages, polyvinyl alcohol (PVA)/EEG nanocomposites were prepared for dielectric application. The prepared nanocomposites had an aligned structure of co-doped EEG (doped with nitrogen and sulfur) and demonstrated excellent dielectric performance. The aligned 4.0 wt% co-doped EEG in the PVA matrix led to a high dielectric constant (201) and low dielectric loss (0.2) in X-band frequency. Different chemical and structural characteristics of the nanocomposite account for the enhanced dielectric properties: (i) good dispersion of co-doped EEG in the polymer matrix, (ii) enhanced polarization centers in the graphene due to nitrogen/sulfur doping, (iii) aligned co-doped EEG sheets, (iv) functional groups at the surface of EEG as barriers between graphene sheets. In the third phase of this thesis, a modified minimally intensive layer delamination (MILD) synthesis approach was introduced to synthesize a highly conductive Ti3C2Tx MXene. By utilizing the modified approach, the electrical conductivity was significantly improved to 2.4 ×〖10〗^4 S/cm, five times more than that obtained from traditional MILD approach which is about 5.8 ×〖10〗^3 S/cm. This significant improvement in electrical conductivity was attributed to better quality of the synthesized MXene with the modified approach as well as higher flake sizes. Furthermore, the modified approach enhanced the synthesis aspects such as synthesis yield (up to ⁓ 60%) and MXene colloidal concentration (up to 31 mg/ml). The prepared MXene demonstrated a promising application as a supercapacitor, with a high capacitance of ⁓ 490 F/g at 1 A/g. Our synthesis approach has great potential to be used as the next MXene synthesis (etching) approach since it demonstrates improved synthesis yield, high colloidal concentration, and enhanced electrical conductivity.	en_US
dc.identifier.citation	Shayesteh-Zeraati, A. (2020). Synthesis of Multifunctional One-dimensional and Two-dimensional Highly Conductive Nanomaterials for Charge Storage Applications (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/37529
dc.identifier.uri	http://hdl.handle.net/1880/111584
dc.language.iso	eng	en_US
dc.publisher.faculty	Schulich School of Engineering	en_US
dc.publisher.institution	University of Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.subject.classification	Education--Sciences	en_US
dc.subject.classification	Energy	en_US
dc.subject.classification	Engineering	en_US
dc.subject.classification	Materials Science	en_US
dc.title	Synthesis of Multifunctional One-dimensional and Two-dimensional Highly Conductive Nanomaterials for Charge Storage Applications	en_US
dc.type	doctoral thesis	en_US
thesis.degree.discipline	Engineering – Chemical & Petroleum	en_US
thesis.degree.grantor	University of Calgary	en_US
thesis.degree.name	Doctor of Philosophy (PhD)	en_US
ucalgary.item.requestcopy	true	en_US