Hydrogen adsorption by perforated graphene

Abstract

We performed a combined theoretical and experimental study of hydrogen adsorption in graphene systems with defect-induced additional porosity. It is demonstrated that perforation of graphene sheets results in increase of theoretically possible surface areas beyond the limits of ideal defect-free graphene (~2700 m 2 /g) with the values approaching ~5000 m 2 /g. This in turn implies promising hydrogen storage capacities up to 6.5 wt% at 77 K, estimated from classical Grand canonical Monte Carlo simulations. Hydrogen sorption was studied for the samples of defected graphene with surface area of ~2900 m 2 /g prepared using exfoliation of graphite oxide followed by KOH activation. The BET surface area of studied samples thus exceeded the value of single-layered graphene. Hydrogen uptake measured at 77 K and 296 K amounts to 5.5 wt% (30 bar) and to 0.89 wt% (120 bar), respectively.

Graphene decorated with metal nanoparticles: Hydrogen sorption and related artefacts

“…In agreement with theory, our recent experiments demonstrated that hydrogen sorption by r-GO and KOH activated r-GO (a-r-GO) follows standard trends and correlates with SSA values (~100-3300 m 2 /g range in our experiments) both at room temperature and 77K. [32][33][34] Nevertheless, reports on extremely high hydrogen uptakes (either in absolute values or relative to reported SSA) by various types of r-GO continue to appear, [35] outnumbering studies which find trivial uptake numbers. [36] In several cases the data presented as an evidence for exceptional hydrogen storage of graphene are represented by abnormal shapes of isotherms [35,37] or obtained by rather uncommon measurement methods.…”

Hydrogen storage in high surface area graphene scaffolds

“…Recent theoretical modelling results demonstrated that SSA values as high as 5000 m 2 /g are possible for graphene sheets perforated with small size holes and packed into 3D structure with optimal inter-layer distance of 0.7-1 nm. 15 However, the experimental realization of ordered structures proposed in ref. 15 is hindered by the absence of suitable methods to hold graphene layers separate from each other.…”

“…15 However, the experimental realization of ordered structures proposed in ref. 15 is hindered by the absence of suitable methods to hold graphene layers separate from each other.…”

Morphing Graphene-Based Systems for Applications: Perspectives from Simulations

“…A systematic study of the effects of doping on flexoelectricity is currently in the course graphene at 1-2% at room temperature. Besides the obvious strategy of working at cryogenic temperature, in several theoretical works physical interactions were shown enhanced within nanocavities produced by rippling [58], within multilayers with specific (nanometric) interlayer spacing [59,60] or with nanosized perforations of the sheet [61]. From the methodological point of view, it is interesting to observe that these works address the problem of physisorption combining different methodologies besides DFT (see Table 2), including classical approaches based on empirical Force Fields, different types of dynamical treatment of hydrogen (QM dynamics, Monte Carlo and thermodynamic evaluation of the adsorption).…”