In-situ Spectroscopic Identification of Hydrogen Binding Sites on Carbon-Based Hydrogen Sorption Materials

New classes of transition metal (TM)-based hydrogen storage materials, namely spillover (weak chemisorption) materials, have been identified in order to try to meet the Department of Energy's (DOE's) volumetric and gravimetric targets for onboard, reversible vehicular hydrogen refueling and storage. It is proposed that enhanced hydrogen storage on TM doped carbons arises due to hydrogen spillover onto the support. The spillover hydrogen (i.e., atomic hydrogen) has often only been inferred from hydrogen adsorption studies. Optical spectroscopies, such as diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), are very useful for detecting adsorbed hydrogen (physisorption) and have the potential confirm the weak chemisorption of hydrogen on sorption-based materials. Recent experimental efforts have focused on the development of well-defined nanostructured TM supported carbon-based materials with improved weak chemisorption kinetics and sorption capacities. Detailed characterization of these hydrogen storage materials by DRIFTS, including the pressure and temperature relationships for the carbon-hydrogen vibrational modes, will be presented.