Mobility of liquids intercalated into the interplane space of graphite oxide as revealed by a combination of 19F NMR, 1H NMR and EPR spin probe methods

Abstract

A combination of ¹⁹F and ¹H NMR with the Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence was used to examine the mobility of liquids in the interplane space of graphite oxide (GO) for the first time. The proposed approach allows for the reduction of NMR signals from immobile hydrogen-containing groups on the surface of GO and for monitoring of the molecular mobility of intercalated liquids. The mobile fractions of H₂O, CH₃CN and CF₃CH₂OH were detected inside the corresponding swollen GO samples. For H₂O, the amount of mobile liquid showed a peculiar temperature dependence where a certain portion survived well below 273 K. The sensitivity of the proposed ¹H NMR + CPMG procedure is also compared to the sensitivity of the EPR nitroxide spin probe method.