Hydrogen uptake of high surface area-activated carbons doped with nitrogen

Three activated carbons (ACs) having apparent surface areas higher than 2500 m2/g were doped with nitrogen by treatment with urea at 623 K under air flow. Nitrogen contents as high as 15.1 wt.% were obtained, but resulting in decreased surface areas and pore volumes. Hydrogen storage capacities of ACs before and after nitrogen doping were measured at 77 K and up to 8 MPa. After doping, the hydrogen uptake was lower due to the corresponding decrease of surface area. Statistical, ANOVA, analysis of the relevancy of surface area and nitrogen content on hydrogen storage at 77 K was carried out, taking into account our data and those data available in the open literature. We concluded that surface area controls hydrogen adsorption and nitrogen content is not a relevant parameter.