High-pressure hydrogen storage in zeolite-templated carbon

High-pressure hydrogen storage in zeolite-templated carbon (ZTC) was investigated at room temperature (30 °C). Several types of ZTCs with different surface areas and a nitrogen-doped ZTC were prepared. Their hydrogen storage performance at room temperature was examined and the results were compared with those of commercial activated carbons. At pressures below 10 MPa, the hydrogen uptake capacity was simply proportional to specific surface areas of the carbons, and both ZTCs and activated carbon showed almost the same heat of adsorption (6̃8 kJ mol^-1). On the other hand, at pressures above 10 MPa, uniform micropores with a diameter of 1.2 nm in ZTCs played a more important role in capacity increase than the specific surface area. As a result, the ZTC with the largest surface area (3370 m² g ^-1) exhibited hydrogen uptake as high as 2.2 wt % at 34 MPa. This value is much larger than that of the activated carbon, and such a difference in the capacity between ZTC and activated carbon cannot be explained by the difference in specific surface area alone. Moreover, by loading only a small amount of Pt nanoparticles (ca. 0.2 wt %) onto ZTC, hydrogen uptake capacity was increased from 0.87 to 0.95 wt % at 10 MPa. The increase of hydrogen uptake capacity by Pt loading can be ascribed to hydrogen spillover through the supported Pt nanoparticles to the carbon surface.