Hydrogen adsorption on graphene decorated with palladium dimers: a bonding study

I.LÓPEZ-CORRAL, E. GERMÁN, A. JUAN, M. A. VOLPE, G. P. BRIZUELA

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2012 vol. 37 p. 6653 - 6665

0360-3199

We report a density-functional theory study of dihydrogen adsorption on a graphene sheet functionalized with palladium dimers considering different adsorption sites on the carbon surface and both molecular and dissociative Pd2H2 coordination structures. Our results show that a (PdH)2 ring without an HeH bond and not dissociative Pd2(H2) complexes are stable adsorbed systems with more elongated PdPd and PdeH bonds compared to the unsupported configurations caused by CePd interactions. In contrast, individual Pd atoms supported on graphene react with H2 to form only a Pd(H2) complex with a relaxed but not dissociated HeH bond. We also performed the Mulliken analysis to study the bonding mechanism during the adsorption process. In most cases, we found donor-acceptor CPd and PdH interactions in which C 2p, Pd 5s, and H 1s orbitals played an important role. We also found that the adsorption of a second Pd atom close to a PdH2 system destabilizes the HH bond. In this work we contribute to shed more light on the relation between Pd clustering and the possibility of hydrogen storage in graphene-based materials.