Hydrogen storage inside graphene-oxide frameworks

Abstract

In this paper, we use applied mathematical modelling to investigate the storage of hydrogen molecules inside graphene-oxide frameworks, which comprise two parallel graphenes rigidly separated by perpendicular ligands. Hydrogen uptake is calculated for graphene-oxide frameworks using the continuous approximation and an equation of state for both the bulk and adsorption gas phases. We first validate our approach by obtaining results for two parallel graphene sheets. This result agrees well with an existing theoretical result, namely 1.85 wt% from our calculations, and 2 wt% arising from an ab initio and grand canonical Monte Carlo calculation. This provides confidence to the determination of the hydrogen uptake for the four graphene-oxide frameworks, GOF-120, GOF-66, GOF-28 and GOF-6, and we obtain 1.68, 2, 6.33 and 0 wt%, respectively. The high value obtained for GOF-28 may be partly explained by the fact that the benzenediboronic acid pillars between graphene sheets not only provide mechanical support and porous spaces for the molecular structure but also provide the higher binding energy to enhance the hydrogen storage inside graphene-oxide frameworks. For the other three structures, this binding energy is not as large in comparison to that of GOF-28 and this effect diminishes as the ligand density decreases. In the absence of conflicting data, the present work indicates GOF-28 as a likely contender for practical hydrogen storage.

Graphene oxide: A promising nanomaterial for energy and environmental applications

“…By adopting various linear boronic acid pillaring units, the interlayer spacing between graphene planes can be tuned to an optimum value for H 2 adsorption on both surfaces, which is twice of typical porous carbon materials and comparable to MOFs. The outstanding hydrogen storage properties are attributed to the porous spaces, and the enhanced hydrogen adsorption is mainly caused by the benzenediboronic acid pillars between graphene sheets [65]. By modulating the intercalation via three kinds of diaminoalkanes between GO layers, Kim et al [66] found an optimum GO interlayer distance of 6.3 Å with maximum H 2 uptake, similar to the predicted distance from thermally modulated GO [53].…”

“…As shown in Figure 5, graphene oxide frameworks (GOFs) with 3D porosity was synthesized by intercalating the boronic acid (which can react with the hydroxyl groups) into GO layers, which showed superior hydrogen adsorption behavior [63][64][65]. By adopting various linear boronic acid pillaring units, the interlayer spacing between graphene planes can be tuned to an optimum value for H 2 adsorption on both surfaces, which is twice of typical porous carbon materials and comparable to MOFs.…”

Environmental applications using graphene composites: water remediation and gas adsorption

“…Calculations have shown that a GO framework (GOF) which can be prepared from GO and benzenediboronic acid could be used for hydrogen adsorption (Fig. 13b), 170,171 predicting that the GOF can theoretically achieve 6.1 wt% H 2 uptake at 77 K and 1 bar. However, the experimental studies only showed a maximum uptake of 1 wt %.…”

Application of GO in Energy Conversion and Storage

“…The GOFs exhibit high isosteric heat of adsorption and hydrogen adsorption capacity (twice of typical porous carbon material and comparable to MOFs). Based on the reported porous GOFs, Chan et al [45] investigated the hydrogen storage properties of GOFs (GOF-120, GOF-66, GOF-28 and GOF-6) with a mathematic model and found that the GOF-28 has highest hydrogen uptake of 6.33 wt%. The outstanding hydrogen storage properties are attributed to the porous spaces; most importantly the enhanced hydrogen adsorption is caused by the benzenediboronic acid pillars between graphene sheets.…”