I synthesis graphene aerogels via chemical reduction. Briefly, 160 mg L-ascorbic acid was added to 20 ml GO solution (2mg/ml). Then the 20 ml closed vial was heated to 95 oC and maintained in 5h. The obtained graphene hydrogel was put in a freezer at -60 oC for a day and then freeze dried in 2 days.
Graphene aerogel was not mechanically strong as I expected.
I've tried to treat graphene hydrogel in ammonia solution 10% before freeze drying according to this article but it doesn't strengthen graphene aerogel much.
Is there something I need to pay attention to during freeze drying process?
I'm looking for a green and easy method to overcome this problem.
Thank you.
http://pubs.rsc.org/en/content/articlelanding/2013/nr/c3nr00971h#!divAbstract
When I began reading query, I immediately remember an experiment I performed 60 years ago (obviously I was a kid). I put ascorbic acid tablets in a plastic amber bottle with lid partially on onto the west window sill in Bakersfield during the summertime. Next day I noticed crusty black volcanic spew on the wall. I thought was carbon as a 10 y/o. I also melted a sugar cube in a spoon over flame but by first adding a speck of carbon it all morphed black. The cube into con. sulfuric a. also went volcanic. Never saw any graphene except opposite the eraser. All these formed amorphous carbon. The graphene aerogel uses pillars of CNTs so a certain amount of ammonia is needed at edges and corners to act like glue to maintain the assemblage. Unless the planar region of graphene is functionalized not much would be of support except maybe buckminsterfullerene. And, I wouldn't remove ALL of the water. Graphene Exfoliation is done by plasma and chemically. Plasma functionalizes more 'bonding sites' (for ammonia to connect).
I am facing the same issue.Some of my samples got destroyed after freeze-drying.Were you able to solve the issue?Please let me know
not to stray out of the topic but can anyone suggest any paperson the advatagesof using these graphene aerogels on fuel cell applications.
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