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DS: Fachverband Dünne Schichten

DS 35: Graphen

DS 35.12: Vortrag

Donnerstag, 19. März 2015, 12:30–12:45, H 0111

Humidity dependent oxygen transport through single layer graphene oxide — •Mohammad Fardin Gholami, Phillip Lange, Nikolai Severin, and Jürgen P. Rabe — Department of Physics and IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany

Graphene oxide (GO) is a strongly oxidized and nano-porous single sheet of graphene. Few layer thick GO membranes have been shown to exhibit molecular selective gas transport (H.W. Kim et al. and H. Li et al., Science, 2013). The molecular selectivity is humidity dependent, which has been attributed to water molecules blocking either GO interlayers or pores. The latter would imply that also single layer GO may exhibit similar properties. Here we used the sensitivity of the fluorescence of thin films of a regioregular poly(3-hexylthiophene-2,5-diyl) to photo-oxidation in order to investigate the transport of oxygen through single layer GOs put on the polymer films by following its fluorescence decaying with time (P. Lange et al., J. Phys. Chem. C, 2011). For samples exposed to humid mixtures of 80% nitrogen and 20% oxygen with 32% relative humidity we find that the fluorescence of the polymer covered by GO decays two times slower than the uncovered one. We did not observe any difference in the decay rates when the film was exposed to the corresponding dry gas mixture. We attribute the slower fluorescence decay of the polymer film covered by the humidified GO to slower permeation of oxygen molecules through GO pores clogged by the water molecules. This implies that even single layer GO can be used as a humidity dependent molecular sieve.