Influence of structural heterogeneity of nanoporous sorbent walls on hydrogen storage

• Published in: Applied surface science 2010-06, Vol.256 (17), p.5270-5274
• Main Authors: Kuchta, B., Firlej, L., Roszak, Sz, P.Pfeifer, Wexler, C.
• Format: Article
• Language: English
• Subjects: Adsorption; Boron; Carbon; Computational Physics; Computer simulation; Computer simulations; Condensed Matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Heterogeneity; Hydrogen; Hydrogen storage; Materials Science; Monte Carlo methods; Nanostructure; Physics; Porosity; Surface chemistry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2009.12.116

Heterogeneity is an ubiquitous aspect of adsorption, often modifying substantially the observed behaviour of the adsorbate–adsorbent system. In this paper, the influence of heterogeneity is explicitly analyzed for the case of the adsorption of molecular hydrogen onto nanoporous carbon. Grand Canonical Monte Carlo simulations were used to study the mechanism of adsorption in the models of the adsorbate that include both energetic and structural modifications of graphene-based slit pores. In particular, a partial substitution of carbons by boron modifies both the symmetry of the energy landscape and the strength of hydrogen physisorption; which results in considerable increases of the amount of adsorbed gas without major modification of the mechanism of adsorption. Additional heterogeneity arises from structural modifications of the adsorbent by neutron irradiation of boron-doped samples, where the boron fission products generate additional surface area for adsorption. Simulations of adsorption in such pores show that hydrogen uptake is strongly dependent on the chemical nature of the modified pore walls.