Tuning the grade of graphene: Gamma ray irradiation of free-standing graphene oxide films in gaseous phase

Ludovic F. Dumée, Chunfang Feng, Li He, Francois Marie Allioux, Zhifeng Yi, Weimin Gao, Connie Banos, Justin B. Davies, Lingxue Kong

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

A direct approach to functionalize and reduce pre-shaped graphene oxide 3D architectures is demonstrated by gamma ray irradiation in gaseous phase under analytical grade air, N 2 or H 2 . The formation of radicals upon gamma ray irradiation is shown to lead to surface functionalization of the graphene oxide sheets. The reduction degree of graphene oxide, which can be controlled through varying the γ-ray total dose irradiation, leads to the synthesis of highly crystalline and near defect-free graphene based materials. The crystalline structure of the graphene oxide and γ-ray reduced graphene oxide was investigated by x-ray diffraction and Raman spectroscopy. The results reveal no noticeable changes in the size of sp2 graphitic structures for the range of tested gases and total exposure doses suggesting that the irradiation in gaseous phase does not damage the graphene crystalline domains. As confirmed by X-ray photoemission spectroscopy, the C/O ratio of γ-ray reduced graphene oxide is increasing from 2.37 for graphene oxide to 6.25 upon irradiation in hydrogen gas. The removal of oxygen atoms with this reduction process in hydrogen results in a sharp 400 times increase of the electrical conductivity of γ-ray reduced graphene oxide from 0.05 S cm -1 to as high as 23 S cm -1 . A significant increase of the contact angle of the γ-ray reduced graphene oxide bucky-papers and weakened oxygen rich groups characteristic peaks across the Fourier transform infrared spectra further illustrate the efficacy of the γ-ray reduction process. A mechanism correlating the interaction between hydrogen radicals formed upon γ-ray irradiation of hydrogen gas and the oxygen rich groups on the surface of the graphene oxide bucky-papers is proposed, in order to contribute to the synthesis of reduced graphene materials through solution-free chemistry routes.

Original languageBritish English
Pages (from-to)126-135
Number of pages10
JournalApplied Surface Science
Volume322
DOIs
StatePublished - 15 Dec 2014

Keywords

  • bucky-papers
  • Gamma irradiation
  • Graphene oxide reduction and graphene
  • Radiation chemistry
  • Solution-free chemistry

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