title: A New Raman Metric for the Characterisation of Graphene oxide and its Derivatives.
abstract: Raman spectroscopy is among the primary techniques for the characterisation of graphene materials, as it provides insights into the quality of measured graphenes including their structure and conductivity as well as the presence of dopants. However, our ability to draw conclusions based on such spectra is limited by a lack of understanding regarding the origins of the peaks. Consequently, traditional characterisation techniques, which estimate the quality of the graphene material using the intensity ratio between the D and the G peaks, are unreliable for both GO and rGO. Herein we reanalyse the Raman spectra of graphenes and show that traditional methods rely upon an apparent G peak which is in fact a superposition of the G and D' peaks. We use this understanding to develop a new Raman characterisation method for graphenes that considers the D' peak by using its overtone the 2D'. We demonstrate the superiority and consistency of this method for calculating the oxygen content of graphenes, and use the relationship between the D' peak and graphene quality to define three regimes. This has important implications for purification techniques because, once GO is reduced beyond a critical threshold, further reduction offers limited gain in conductivity.
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.|Department of Physics, University of Surrey, Guildford, GU2 7XH, UK.
authors.forename: Alice A K
authors.initials: AA
authors.lastname: King
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.|Biomaterials and Tissue Engineering Research Unit, University of Sydney, NSW, 2006, Australia.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Davies
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.
authors.forename: Nikan
authors.initials: N
authors.lastname: Noorbehesht
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.|Biomaterials and Tissue Engineering Research Unit, University of Sydney, NSW, 2006, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Newman
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Church
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Harris
authors.affiliation: ARC Future Fellow, Institute for Frontier Materials, Deakin University, Geelong, Australia.
authors.forename: Joselito M
authors.initials: JM
authors.lastname: Razal
authors.affiliation: Laboratory for Sustainable Technology, Department of Chemical and Biomolecular Engineering, University of Sydney, NSW, 2006, Australia.|Australian Institute for NanoScience and Technology (AINST), University of Sydney, NSW, 2006.
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Minett