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Carbocatalysts: Graphene Oxide and Its Derivatives

TitleCarbocatalysts: Graphene Oxide and Its Derivatives
Publication TypeJournal Article
Year of Publication2013
AuthorsSu, Chenliang, and Loh Kian Ping
JournalAccounts of Chemical Research
Date Published10/2013

Graphene oxide ({GO)} sheets are emerging as a new class of carbocatalysts. Conventionally, researchers exfoliate graphite oxide into submicrometer-sized, water-dispersible flakes to produce these sheets. The presence of oxygen functional groups on the aromatic scaffold of {GO} allows these sheets to mediate ionic and nonionic interactions with a wide range of molecules. {GO} shows remarkable catalytic properties on its own and when hybridized with a second material. It is a perfect platform for molecular engineering. This Account examines the different classes of synthetic transformations catalyzed by {GO} and correlates its reactivity with chemical properties. First, we raise the question of whether {GO} behaves as a reactant or catalyst during oxidation. Due to its myriad oxygen atoms, {GO} can function as an oxidant during anaerobic oxidation and become reduced at the end of the first catalytic cycle. However, partially reduced {GO} can continue to activate molecular oxygen during aerobic oxidation. Most importantly, we can enhance the conversion and selectivity by engineering the morphology and functionalities on the {G/GO} scaffold. {GO} can also be hybridized with organic dyes or organocatalysts. The photosensitization by dyes and facile charge transfer across the graphene interface produce synergistic effects that enhance catalytic conversion. Using {GO} as a building block in supramolecular chemistry, we can extend the scope of functionalities in {GO} hybrids. The presence of epoxy and hydroxyl functional groups on either side of the {GO} sheet imparts bifunctional properties that allow it to act as a structural node within metal?organic frameworks ({MOFs).} For example, known homogeneous molecular catalysts can be anchored on the {GO} surface by employing them as scaffolds linking organometallic nodes. We have demonstrated that porphyrin building blocks with {GO} can lead to facile four-electron oxygen transfer reactions. We have also evaluated the advantages and disadvantages of {GO} as a catalytic material relative to other types of catalysts, both metallic and nonmetallic. Researchers would like to increase the potency of {GO} catalysts because many catalytic reactions currently require high loading of {GO.} Further research is also needed to identify a low-cost and environmentally friendly method for the synthesis of {GO.}


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