Skip to main content Accessibility help
×
Home

Contents:

Information:

  • Access

Actions:

      • Send article to Kindle

        To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

        Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

        Find out more about the Kindle Personal Document Service.

        Nano Focus: Electronic properties of graphene modulated with chemical functionalization
        Available formats
        ×

        Send article to Dropbox

        To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

        Nano Focus: Electronic properties of graphene modulated with chemical functionalization
        Available formats
        ×

        Send article to Google Drive

        To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

        Nano Focus: Electronic properties of graphene modulated with chemical functionalization
        Available formats
        ×
Export citation

Graphene, with its two-dimensional, hexagonal honeycomb lattice structure and semimetallic characteristics, has great potential for use in a diverse array of optoelectronic applications, especially now that synthetic routes for its large-scale synthesis have been demonstrated. One route to achieving this goal is through chemical functionalization, which can convert graphene, with its bandgap of zero, to a wide-bandgap semiconductor. In addition, patterned multifunctional regions could be used to form the superlattices required for devices such as chemical sensors and thermoelectrics. Toward these ends, J.M. Tour and colleagues at Rice University and Tianjin University have demonstrated a two-step process to first hydrogenate a pattern on the basal plane of graphene and then convert the hydrogens to a different functionality.

As reported in the November 29, 2011 issue of Nature Communications (DOI: 10.1038/ncomms1577), the researchers transferred graphene originally grown on Cu substrates to an insulating substrate (either quartz or SiO2/Si) and then used conventional lithography to expose defined regions of the graphene to atomic hydrogen. Fluorescence quenching microscopy (FQM) was used to image the regions of hydrogenated graphene, which are termed graphane; see (a) in the figure. Partial hydrogenation of the graphene was confirmed using Raman spectroscopy. Measurement of the electronic properties of this material using four-probe analysis demonstrated a gradual transformation from semimetallic graphene to a near insulating graphane-like material with increasing hydrogenation.

The researchers also further functionalized the graphene/graphane superlattice with 4-bromophenyldiazonium tetrafluoroborate. They proposed that spontaneous electron transfer occurs from the graphane to the diazonium salt, generating an aryl radical that attacks the sp 3 C–H bonds to form new, covalent sp 3 C–C bonds; see (b) in the figure. Transmission electron microscopy and electron diffraction patterns of the diazonium functionalized films confirmed that the graphene structure survives the functionalization reactions. The extent of diazonium functionality was investigated using x-ray photoelectron spectroscopy, which showed that functionalized films containing as much as one new sp 3 C–C bond for every 21.5 C atoms in the graphane domains could be achieved using this methodology.

The researchers said that their “two-step controlled covalent functionalization process permits modulation of the electronic properties of graphene’s basal planes and could hold promise for specifically patterned optoelectronic and sensor devices based on this exciting new material.”

(a) Images of graphane/graphene patterns revealed with fluorescence quenching microscopy (FQM); the scale bars are 200 μm; (b) the fabrication of sp 3 C–C exchanged superlattices and subsequent FQM imaging is illustrated with a schematic diagram. Reproduced with permission from Nat. Commun. 2:527, DOI: 10.1038/ncomms1531. © 2011 Macmillan Publishers Ltd.