ACCELERATED FIRST-PRINCIPLES MOLECULAR DYNAMICS TO STUDY HYDROGEN INTERACTION WITH TRANSITION METAL DOPED CARBON MATERIALS

摘要

Hydrogen is involved in a large number of catalytic reactions and a significantly important class of catalytic material in hydrogen involving reactions consists of transition metal clusters anchored on a support, particularly a carbon based support. After (i) the sp~2 type carbon based materials like nanotubes, activated carbon and activated carbon fibers have been recognized as potential hydrogen storage materials and (ii) transition metal doping has demonstrated an increase in the hydrogen storage capacities of such materials, the interaction of hydrogen with these materials has become the focus of interest for hydrogen storage. The nature of hydrogen bonding (physisorption or chemisorption) and the possibility of its dissociation and migration on the catalyst material are the key factors governing the functionality of these materials. Though of great importance, the interaction mechanism of hydrogen with metal-doped carbon materials is mostly studied by interpreting experimental data for a combination of sequential steps in the entire catalysis process and the deficiency of isolated studies of hydrogen interaction with these materials has left some doubts about its mechanism and dynamics, the existence of spillover, the energetics of the process and the process of desorption of monoatomic hydrogen in the form of diatomic hydrogen molecule. In the present paper, for the first time, we have attempted to model simultaneously the finite temperature dynamics and energetics of the interaction of hydrogen with a carbon supported Pd cluster.