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Functional Properties of Mechanically Exfoliated Graphene

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Maloney, Thaddeus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
dc.contributor.author Phiri, Josphat
dc.date.accessioned 2019-12-04T10:01:36Z
dc.date.available 2019-12-04T10:01:36Z
dc.date.issued 2019
dc.identifier.isbn 978-952-60-8863-1 (electronic)
dc.identifier.isbn 978-952-60-8862-4 (printed)
dc.identifier.issn 1799-4942 (electronic)
dc.identifier.issn 1799-4934 (printed)
dc.identifier.issn 1799-4934 (ISSN-L)
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/41390
dc.description.abstract Graphene is an exciting 2-dimensional material with a wide range of superior properties, such as excellent thermal and electrical conductivity, high transparency, surface area and mechanical strength. However, a wider scale application still depends on finding viable large-scale production methods of high quality graphene. This thesis demonstrates a feasible method for fabrication of graphene with scalability potential. High concentration and quality of mechanically exfoliated graphene (in short, pristine graphene), was achieved at short processing time using shear exfoliation. This mechanically exfoliated graphene was further used to fabricate functional nanopapers with a wide range of properties, and as electrode materials for supercapacitor application. The properties of pristine graphene were also compared to other types of graphene, namely graphene oxide (GO) and reduced graphene oxide (RGO), in nanocomposite films designed for functional applications formed as graphene-doped microfibrillated cellulose (MFC) nanopapers. The different surface chemistry of these grades of graphene led to the fabrication of composites with a wide range of properties due to their unique interaction with the MFC polymer matrix. For example, pristine graphene led to a high electrical conductivity and thermal stability, while GO and RGO led to enhanced mechanical properties of the nanopapers. The composites can be tailored for a wide range of potential applications, such as flexible electronics, sensors, electrodes etc. Following these foreseen advantages, the nanopapers were further developed for testing in application as electrode materials in supercapacitors. This was realized by converting into carbon hybrids by activation with KOH to introduce properties suitable for good electrochemical performance. MFC was used to stabilize and exfoliate the graphene and as a binder in the electrodes. The electrodes showed excellent electrochemical performance with potential for application in various devices. Furthermore, the performance of the carbon hybrids was compared with willow-derived activated carbon in supercapacitors. The willow-derived activated carbon showed even higher capacitance than the carbon hybrids. However, the carbon hybrids showed much better cycling stability, 99% capacitance retention after 5 000 cycles versus 94% for willow derived activated carbons. The work summarized in this thesis, in conclusion, contributes to the development of graphene for larger scale commercial application, identifying potential routes for fabrication of high performance functional carbon materials based on alternative renewable and sustainable materials to replace the currently potentially toxic, and hazardous chemical additives. en
dc.format.extent 95 + app. 87
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series DOCTORAL DISSERTATIONS en
dc.relation.ispartofseries 228/2019
dc.relation.haspart [Publication 1]: Phiri, J., Gane, P., Maloney, T.C. High-concentration shear-exfoliated colloidal dispersion of surfactant–polymer-stabilized few-layer graphene sheets. Journal of Materials Science, 2017, 52(13), 8321-8337. Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201905062697. DOI: 10.1007/s10853-017-1049-y
dc.relation.haspart [Publication 2]: Phiri, J., Johansson, L.S., Gane, P., Maloney, T.C. Co-exfoliation and fabrication of graphene based microfibrillated cellulose composites–mechanical and thermal stability and functional conductive properties. Nanoscale, 2018, 10(20), 9569-9582. Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201905062784. DOI: 10.1039/C8NR02052C
dc.relation.haspart [Publication 3]: Phiri, J., Johansson, L.S., Gane, P., Maloney, T. A comparative study of mechanical, thermal and electrical properties of graphene-, graphene oxideand reduced graphene oxide-doped microfibrillated cellulose nanocomposites. Composites Part B: Engineering, 2018, 147, 104-113. Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201905062745. DOI: 10.1016/j.compositesb.2018.04.018
dc.relation.haspart [Publication 4]: Phiri, J., Gane, P., Maloney, T.C. Multidimensional Co‐Exfoliated Activated Graphene‐Based Carbon Composite for Supercapacitor Electrode. Energy Technology. 2019, 7: 1900578. Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201909205307. DOI: 10.1002/ente.201900578
dc.relation.haspart [Publication 5]: Phiri, J., Dou, J., Vuorinen, T., Gane, P.A., Maloney, T.C. Highly Porous Willow Wood-Derived Activated Carbon for High-Performance Supercapacitor Electrodes. ACS Omega, 2019, 4, 19, 18108-18117. DOI: 10.1021/acsomega.9b01977
dc.subject.other Chemistry en
dc.title Functional Properties of Mechanically Exfoliated Graphene en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Kemian tekniikan korkeakoulu fi
dc.contributor.school School of Chemical Technology en
dc.contributor.department Biotuotteiden ja biotekniikan laitos fi
dc.contributor.department Department of Bioproducts and Biosystems en
dc.subject.keyword graphene en
dc.subject.keyword supercapacitor en
dc.subject.keyword electrodes en
dc.subject.keyword graphite en
dc.subject.keyword graphene oxide en
dc.subject.keyword nanocellulose en
dc.subject.keyword microfibrillated cellulose en
dc.subject.keyword energy storage devices en
dc.identifier.urn URN:ISBN:978-952-60-8863-1
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Maloney, Thaddeus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
dc.opn Saarinen, Jarkko J., Prof., University of Eastern Finland, Finland
dc.contributor.lab Biobased Materials Technology en
dc.rev Tuukkanen, Sampo, Prof., Tampere University, Finland
dc.rev Garnier, Gil, Prof., Monash University, Australia
dc.date.defence 2019-12-12
local.aalto.acrisexportstatus checked 2019-12-14_1447
local.aalto.infra Bioeconomy infrastructure
local.aalto.formfolder 2019_12_03_klo_14_50
local.aalto.archive yes

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