Modification of a commercial activated carbon with nitrogen and boron: Hydrogen storage application

Abstract

The present study evaluates the effect of heteroatom doping (N and B) and thermal treatment modification of activated carbon, in different sequences over hydrogen storage capacity. All the materials were characterized by N2-physisorption, XRD, TPD, and XPS. H2 adsorption was measured at −196 °C and correlated with physico-chemical properties, while a density-functional theory model was employed to analyze the hydrogen adsorption. Results have shown that there is an effect of the modification order on the storage capacity, which was related to increments of the specific surface area or the nature of the functional groups. An optimum nitrogen doping temperature was detected at 500 °C and was associated with the presence of pyridone groups. This sample had the highest hydrogen capacity ca. 2.34 % at 0.93 bar. Such value was extrapolated to 7.86 wt% at 30 bar using the Dubinin-Astakhov adsorption model, making it a promising material for hydrogen storage.