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  • Open Access

    ABSTRACT

    Electrical conductivity, chemistry and bonding alternations under graphene oxide to graphene transition as revealed by in-situ TEM

    Zhi Xu, Yoshio Bando, Lei Liu, Wenlong Wang, Xuedong Bai, Dmitri Golberg

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.2, pp. 41-42, 2011, DOI:10.3970/icces.2011.017.041

    Abstract A specially designed suspended graphene oxide (GO) device has been fabricated and investigated in a transmission electron microscope (TEM)-scanning tunneling microscopy (STM) based setup. The detailed study of step-by-step slow reduction of an individual GO sheet under current flow and thereby Joule heating, while in-parallel performing conductivity measurements, atomic structure imaging, chemical composition, and bonding alternations tracing have been performed. As monitored by electron energy core loss spectroscopy, the oxygen content is tuned from that peculiar to a pristine GO, i.e. 23.8 at.%, to oxygen-free pure graphene. Six orders of magnitude conductance rise is achieved during this process with the… More >

  • Open Access

    ARTICLE

    Functionalised Poly(Vinyl Alcohol)/Graphene Oxide as Polymer Composite Electrolyte Membranes

    O. Gil-Castell1,2, R. Cerveró1, R. Teruel-Juanes1, J. D. Badia1,2, A. Ribes-Greus1,*

    Journal of Renewable Materials, Vol.7, No.7, pp. 655-665, 2019, DOI:10.32604/jrm.2019.04401

    Abstract Crosslinked poly(vinyl alcohol) (PVA) based composite films were prepared as polyelectrolyte membranes for low temperature direct ethanol fuel cells (DEFC). The membranes were functionalised by means of the addition of graphene oxide (GO) and sulfonated graphene oxide (SGO) and crosslinked with sulfosuccinic acid (SSA). The chemical structure was corroborated and suitable thermal properties were found. Although the addition of GO and SGO slightly decreased the proton conductivity of the membranes, a significant reduction of the ethanol solution swelling and crossover was encountered, more relevant for those functionalised with SGO. In general, the composite membranes were stable under simulated service conditions.… More >

  • Open Access

    ARTICLE

    Structural and Optical Properties of Graphene Oxide Prepared by Modified Hummers’ Method

    N. Selvakumar1,2, Uday Pradhan1, S.B. Krupanidhi2, Harish C. Barshilia1,*

    CMC-Computers, Materials & Continua, Vol.52, No.3, pp. 175-185, 2016, DOI:10.3970/cmc.2016.052.173

    Abstract Graphene oxide was synthesized from graphite flakes using modified Hummers’ method. The interlayer spacings of graphite, graphite oxide and graphene oxide were measured using X-ray diffraction technique. The C/O atomic ratios of graphite oxide and graphene oxide were calculated from XPS measurements. The transformation of graphite to graphite oxide and finally to graphene oxide was clearly observed from the micro-Raman spectroscopy data and was confirmed from the FESEM micrographs. UV-VIS-NIR spectrophotometer was used to study the absorbance of graphene oxide and reduced graphene oxide samples. Finally, the chemically reduced graphene oxide was heat-treated in air to obtain chemically modified graphene. More >

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