Theory-guided metal-decoration of nanoporous carbon for hydrogen storage applications

Abstract

The current paper presents a combined ab initio and experimental study of H2 adsorption on carbon. Adsorption energetics of a H2 molecule on pristine graphene were obtained for various molecule orientations, showing that the perpendicular-to-surface orientation is energetically more preferable (Eads = −0.076eV/H2) than the parallel orientations (Eads ≈−0.071eV/H2). Subsequently, B, Co, Ni, Pd, Pt and Ru substituents of a C atom in graphene were considered, leading to the conclusion that Pt and Ru promote the H2 adsorption by ≈−0.012eV/H2. Pt promotes adsorption in all its neighbouring hexagons, while Ru impact is localised to the position directly above the dopant. Pure, Pt and Ru-doped ordered mesoporous carbon samples were evaluated experimentally for their H2 adsorption performance under a low-pressure regime (up to 1 bar) at cryogenic and room temperatures (i.e., 77 and 298 K, respectively). These experimental measurements indicated that, while the specific area of the metal-decorated carbons is lower than that of the pristine carbon material, the presence of Pt and Ru nanoparticles leads to a slight improvement of the H2 uptake performance at room temperature.