Nanoclusters of iron oxice included in CMK-3mesoporous carbon use as hydrogen storage material

Abstract

In this work we studied the influence of the incorporation of iron oxide nanoparticles inside the channels of the nanostructured mesoporous carbon CMK-3. This research includes synthesis of the mesoporous silicate and synthesis of CMK-3 by nanocasting strategy, incorporation of the iron oxide nanoclusters by wetness impregnation, characterization of these nanomaterials by XRD, N2 adsorption, XPS, and TEM, and study of the improvement in hydrogen adsorption. This material is promising in hydrogen adsorption and storage application for energy harvesting. According to XRD studies, the incorporation of oxide nanoclusters does not compromise the overall structure of the mesoporous carbon CMK-3. In the wide angle region it has been found typical reflections of iron oxide corresponding to the magnetite phase (Fe2+Fe3+ 2 O4). The modified sample Fe-CMK-3 reveal a reduced specific surface area and smaller pore diameter compared to pristine CMK-3 which involves the formation of magnetite nanoparticles within the mesoporous channels of CMK-3. TEM images of Fe-CMK-3 presents metallic oxide nanoparticles well dispersed. The incorporation of iron oxide nanoparticles improved significantly the H2 storage behavior (4.45% wt at 77K and 10 bar) compared to its respective support (CMK-3). Magnetite nanoclusters increased the capacity of hydrogen adsorption in pristine materials. Supposing that weakly orbital interactions occur between H2 and the metal nanocluster, physisorption is the main interaction, all cases have the potential to uptake H2 weakly as physisorption process and the last interaction achieves sufficiently strong energies to store more hydrogen to reach the level adsorption in Fe-CMK-3. In addition, no hydrogen chemisorption was detected. The materials synthesized are promising in hydrogen uptake by weak link forces (physisorption).