Hydrogen storage in cobalt-embedded ordered mesoporous carbon

Ordered mesoporous carbons (OMCs) were synthesized by using ordered mesoporous silica as a template, and chitosan as carbon precursors. A novel process of pre-impregnation is proposed to prepare cobalt-embedded OMC. This process is based on using cobalt chelated chitosan as carbon precursor. The surface functional groups and metal contents were determined by X-ray photoelectron spectroscopy. The bulk cobalt contents in the cobalt-embedded OMCs were measured by an atomic absorption spectrometer. The morphology of the OMCs was observed by small angle X-ray scattering analysis and transmission electron microscope. The OMC texture characteristics were determined by using nitrogen adsorption analysis. Hydrogen capacities of the OMCs were obtained by a volumetric method. The cobalt-embedded OMCs possess obviously higher hydrogen adsorption capacity than that of pure OMC. At 298 K and under 5.5 MPa, the hydrogen capacities of the OMC and OMC–Co-5 are 0.2 and 0.45 wt%, respectively. The H2/Co ratio of the hydrogen adsorbed on the OMC–Co-5 is 1.54 indicating a Kubas-type interaction between Co and H2. In addition, the hydrogen spillover effect might occur in parallel.

► A novel process of pre-impregnation is proposed.
► Cobalt-embedded OMC was synthesized by Co-chelated chitosan as carbon precursor.
► Hydrogen capacity of cobalt-embedded OMC is obviously higher than that of pure OMS.
► This was due to Kubas interaction and hydrogen spillover.