Abstract
We employed the inelastic neutron scattering (INS) method to directly monitor the change of molecular hydrogen in the Pt-doped activated carbon (Pt/AC) samples and provide very conclusive evidence that significant hydrogen atoms can diffuse to the carbon surface at room temperature during the spillover process. The INS method is uniquely capable of revealing the state of the hydrogen (either the atomic or molecular form). The INS result shows a direct quantitative evaluation of the amount of hydrogen adsorbed on AC in an atomic form via spillover. Two Pt/AC samples with different spillover effects were studied herein. The spillover behavior related to dissociation, diffusion, and adsorption of hydrogen in the Pt/AC samples at the temperature cycling from 4 up to 300 K was investigated by this INS study. The present study proposes the concept of diffusion length and hydrogen-rich domain around a Pt cluster center in this system based on INS data. © 2011 American Chemical Society.