Spin-lattice relaxation time in water graphene oxide solution.
Profeta G., De Thomasis G., Perrozzi F., Fioravanti G., Aschi M., Ottaviano L., Galante A., Alecci M.
VI - Fisica applicata, acceleratori e beni culturali
GSSI Ex ISEF - Aula A - Mercoledì 25 h 16:30 - 19:00
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We present the results of all-atom molecular-dynamics simulations of the spin-lattice relaxation time, pure water, aqueous solutions of graphene and graphene oxides at various concentrations. We show that despite the diamagnetic nature of the graphene oxide, confining effects of GO bi-layers strongly affects the relaxation properties of interfacial water which shows a reduced dynamics due to the hydrogen bonds with oxygen groups on graphene. We found that nanoconfinement of water in bilayer GO systems can be responsible for the shortening of the $T^1$ relaxation time at relevant frequencies for NMR. This same mechanism will be active considering possible structural defects of natural GO, like holes of 10--15 nm, formed on the GO flakes which can be further exploited by the electronic paramagnetic centres formed by graphene dangling bonds and defects, which when coupled by the water dynamics will increase the contrasting properties.