From a chemical point of view, there are at least two requirements for the preparation of a 3D graphene (a nanomaterial formed by cross-linking graphene flakes):

1) solvated graphene-like sheets in solutions which can be obtained for example by liquid exfoliation (see Jonathan Coleman), alkali metal intercalation (see Alain Penicaud), or oxidation by modified Hummer's methods.

2) bifunctional cross-linking agents which should match (in terms of reactivity) the chemical nature of the surface of the solvated graphene flakes.

Arguably,

a) defect-free graphene flakes obtained by liquid exfoliation exhibit an sp2-carbon surface which reacts with diazonium salts. In this case the bis-diazonium salt of 1,4-diaminobenzene or 4,4'-diaminobiphenyl could be the crosslinking agent in the proper conditions (either James Tour or Mohamed M. Chehimi might have already tried this approach). Of course, diazonium salts are not the only reactive agents for sp2-carbon surfaces and the same liquid-exfoliated flakes are expected to react with other crosslinking agents such as bis-adehydes and sarcosine following the 1,3-dipolar cycloaddition introduced by Maggini and Prato or bifunctional nucleophiles (see Andreas Hirsch).

b) the functionalization of graphite intercalated compounds (GICs) might offer interesting opportunities. Milo Shaffer has recently optimized the alkylation of GICs (http://pubs.rsc.org/en/content/articlepdf/2014/TA/C4TA02349H) and that might open the way to 3D graphene by using dihaloalkanes.

c) finally, it might worth a try to follow one of the reported simultaneous reduction and surface functionalization of GO in solution (I like this one by Ruoff: http://onlinelibrary.wiley.com/doi/10.1002/adfm.201001692/abstract) with a bifunctional reduction and functionalization agents and see what happens.

I imagine that two of the critical aspects in these experiments will be the optimization of the reaction conditions in which the crosslinking is favored with respect to the mono-functional functionalization (it might require lots of experiments or a statistical DOE approach) and the optimization of a purification protocol necessary to detect, isolate and characterize the 3D graphene in the arguably heterogeneous reaction products.

HI Habib,

If you are looking for 3D graphene network (like attached file), mentioned by Joachim, PECVD technique works better. For this kind of structure no need to search for any agent, except hydrocarbon source with career gas. This structures known as carbon nanowalls or vertical graphene. To get information regarding that google search will help you.

Otherwise, you can ask without any hesitation.

Best wishes

Subrata

Actually I am bit skeptical about so-called "cross-linked" graphene.. That's another discussion. 

Self assembly is the best way to obtain 3D graphene.. recent trend is growing graphene on metal foam and etching out the substrate.. second method is by freeze dry graphene/polymer gel and remove the polymer.. 

I think It depends on the application. For example,I'd rather Graphene Aerogel in supercapacitors due to its facile synthesis procedure but for sensors GOFs can be better.

Dear Habib Gholipour ,

There are number of ways to synthesize 3D graphene architectures, namely, direct route ( including, CVD, PVCD, graphitization etc.) and solution based synthesis ( including, reduction of GO in solution via chemical reduction or hydro-thermal reduction or freeze drying etc.).

Please, note there is always trade-off between quality of produced graphene. structures, and quantity via different routes of synthesis.

You may check out this article or other published work in the literature.

Article Preparation of 3D graphene-based architectures and their app...

Cheers,

Ali