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    Electrochemical functionalization of graphene nanosheets with catechol derivatives as an effective method for preparation of highly performance supercapacitors

    , Article Electrochimica Acta ; Vol. 147, issue , 2014 , pp. 136-142 ; ISSN: 00134686 Jokar, E ; Shahrokhian, S ; Zad, A. I ; Sharif University of Technology
    Abstract
    Performance enhancement of supercapacitors has been recently discussed. In this paper a novel and facile procedure for functionalization of graphene with some electroactive molecules is presented. The graphene has been functionalized by catechol-based molecules, which are electroactive molecules with electrochemically reversible properties. The functionalized graphene exhibits very effective pseudocapacitor behaviorfor charge storage. For the first time, with the aim of an electrosynthesis procedure, catechol is covalently attached on graphene sheets. This attachment has been investigated by electrochemical, X-ray photoelectron spectroscopy and attenuated total reflectance methods. Catechol... 

    Stable local moments of vacancies, substitutional and hollow site impurities in graphene

    , Article Journal of Physics Condensed Matter ; Volume 27, Issue 15 , 2015 ; 09538984 (ISSN) Mashkoori, M ; Jafari, S. A ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Abstract
    The two-sublattice nature of graphene lattice in conjunction with three-fold rotational symmetry, allows for the p-wave hybridization of the impurity state with the Bloch states of carbon atoms. Such an opportunity is not available in normal metals where the wave function is scalar. The p-wave hybridization function V (-k) appears when dealing with vacancies, substitutional adatoms and the hollow site impurities while the s-wave mixing on graphene lattice pertains only to the top site impurities. In this work, we compare the local moment formation in these two cases and find that the local moments formed by p-wave mixing compared to the s-wave one are robust against the changes in the...