Hydrogen sorption on microporous carbon/sulfur nanocomposite systems

Abstract

Encapsulating sulfur in single-walled carbon nanotubes (S@SWCNTs) produces a composite material hitherto unexplored for hydrogen storage. Interactions between sulfur and carbon nanotubes modify the electronic properties of the composite, thus offering methods for improving hydrogen sorption in carbon nanotubes. Here we demonstrate that S@SWCNT composites can provide 35% greater gravimetric excess adsorbed hydrogen per unit specific surface area, and improved hydrogen uptake at lower pressures (<2 MPa), indicating higher enthalpies of adsorption. Through semi-empirical modelling of high-pressure gas sorption isotherms, it was determined that S@SWCNTs can provide 74% higher volumetric hydrogen density compared to an undoped equivalent at 2 MPa and 77 K.