Wednesday, February 25, 2009

Structure of Graphite Oxide Revisited

Anton Lerf, Heyong He, Michael Forster, Jacek Klinowski (1998). Structure of Graphite Oxide Revisited The Journal of Physical Chemistry B, 102 (23), 4477-4482 DOI: 10.1021/jp9731821

A pre-graphene paper exploring what graphite oxide actually looks like. The authors make graphite oxide from Hummer's method (KMnO4/H2SO4), then fool about with it by pumping it full of things like water, KI, thiourea, NaOH, NaOEt, dioxane, DMSO, and a number of other compounds. They then used a fancy diffraction measurement called a Debey-Sherrer photograph to determine interlayer distances and 13C and 1H magic angle spinning (MAS) NMR to determine structure. They found that water is an intricate part of graphite oxide, and that most of the oxygen that is covalently bound to graphite oxide is in the form of alcohols and epoxides. Although this isn't in the paper, I believe that most of the defects in graphene formed from this method come from the epoxide centers, not the hydroxide centers. The original paper also found that, instead of oxidation happening uniformly over the area of the graphite, there are oxidation-heavy regions and then regions where hardly anything is oxidized.

Moral of the story: Graphite (and graphene) oxide has a lot of water in it, and most of the oxygen is in the form of hydroxyl and epoxide groups.

ResearchBlogging.org