Photocharged by Graphene

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Science  04 Dec 2009:
Vol. 326, Issue 5958, pp. 1323
DOI: 10.1126/science.326.5958.1323-a

Although the basal plane of graphite is relatively unreactive, the unusually high conductivity and zero band-gap of graphene (an isolated single layer of graphite) portend greater reactivity. Liu et al. examined the photoreactivity of benzoyl peroxide with a graphene sheet suspended in toluene. Laser excitation at several visible wavelengths led to the addition of phenyl groups to the graphene surface, and the rate of reaction increased with decreasing irradiation wavelength at the same total power. The reaction did not proceed thermally but could occur at very low laser power. The presence of air only led to unrelated photo-oxidation reactions. The authors argue that the reaction proceeds through a hot-electron mechanism, in which a surface-adsorbed benzoyl peroxide molecule accepts a photoelectron ejected from graphene into its lowest unoccupied orbital, and then decomposes into phenyl radicals.

J. Am. Chem. Soc. 131, 10.1021/ja9043906 (2009).

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