The journal (Graphene, ASP) ceased operations and the DOI infrastructure went dark. The paper itself is archived at ResearchGate: researchgate.net/publication/258423577. The content is independently verifiable.

I wanted to check the journal where it was published, there are good journals and bad journals.It's very strange that the doi is dead. I found this http://www.aspbs.com/graphene/contents_graphene2013.htm but it's also full of dead links.