Sorption of 4He, H2, Ne, N2, CH4, and Kr impurities in graphene oxide at low temperatures. Quantum effects

Abstract

Sorption and the subsequent desorption of 4 He, H 2 ,Ne, N 2 , CH 4 and Kr gas impurities by graphene oxide (GO), glucose-reduced GO (RGO-Gl) and hydrazine-reduced GO (RGO-Hz) powders have been investigated in the temperature interval 2-290 K. It has been found that the sorptive capacity of the reduced sample RGO-Hz is three to six times higher than that of GO. The reduction of GO with glucose has only a slight effect on its sorptive properties. The temperature dependences of the diffusion coefficients of the GO, RGO-Gl and RGO-Hz samples have been obtained using the measured characteristic times of sorption. It is assumed that the temperature dependences of the diffusion coefficients are determined by the competition of the thermally activated and tunneling mechanisms, the tunneling contribution being dominant at low temperatures.

The effect of the thermal reduction on the kinetics of low-temperature 4He sorption and the structural characteristics of graphene oxide

“…Tunnel diffusion of light impurities at low temperatures was also observed in other carbon nanostructures, specifically in carbon nanotubes [21,22] and fullerite C 60 [23][24][25]. This led us to assume that the kinetics of gas sorption by carbon nanostructures was significantly influenced by the potential relief of their surfaces.…”

“…Owing to their advantageous characteristics, such as low density, chemical stability, diversity of structural forms, easy-to-modify porous structure, surface susceptible to a variety of treatment techniques and relatively simple technologies of industrial-scale production, graphene -based materials hold considerable potential for development of gas storage technologies, adsorption/desorption of impurity particles among them. Previously we investigated the sorption and the subsequent desorption of 4 He, H 2 , Ne, N 2 , CH 4 and Kr by glucose-and hydrazine-reduced GO [20]. It was found that in the temperature interval 2-290 K, the temperature dependences of the diffusion coefficients of light impurities (hydrogen and helium) were controlled by a competition between the thermally activated and tunnel mechanisms of diffusion.…”

“…This led us to assume that the kinetics of gas sorption by carbon nanostructures was significantly influenced by the potential relief of their surfaces. Furthermore, it was found that oFGs also had a significant effect on the sorption properties of graphene oxide [20]: the sorption capacity of GO increased three-to six-fold after removing oFGs through hydrazine-reduction. The result suggests that the removal of oFGs via hydrazine reduction unblocks the interlayer space in GO and allows the gas impurities to penetrate inside through the defects on the graphene surface.…”

Effect of γ-ray irradiation on the sorption of hydrogen by nanoporous carbon materials

“…3) for the synthetic SCN sorbent (initial and irradiated in hydrogen atmosphere), closed-end single-wall carbon nanotubes (SWNT) (initial and irradiated in a hydrogen atmosphere) 5 and the hydrazine reduction of graphene oxide (RGO-Hz) 9 shows that the hydrogen-atmosphere irradiated SCN sorbent was the most effective in terms of low-temperature hydrogen sorption under equal saturation conditions.…”

“…3). Judging by the desorption diagram for reduced graphene oxide, 9 there are no pores with such small parameters in RGO-Hz.…”