Francesca Costanzo, Marc C. van Hemert and Geert-Jan KroesFaculty of Science, Leiden Institute of Chemistry, Theoretical ChemistryEinsteinweg 55, 2333 CC LeidenIn this work we investigate the dissociation of H2 on Aln(n=2,4,6) clusters supported by coronene and graphene substrates using density functional theory (DFT), where coronene is taken as a model for graphene. The interaction of metal cluster and graphene occurs through physisorption or chemisorption; the physisorption interaction involves a possible charge transfer (CT) and does not involve a chemical bonding, thereby preserving graphene's intrinsic p bond structure. The binding energies, the distances, and the active molecular orbitals, are consistent with both of these mechanisms are present.Calculations of Aln interacting with coronene show that coronene stabilizes the Aln clusters for any size of the cluster studied in the singlet state, which is most favorable for H2dissociation. Analysis of the electrostatic energy and charge population shows that � 20 % of the overstabilization is due to a CT between the Al atoms and the coronene molecule.We also explore several chemisorbed dissociated states of H2 on the Al clusters supported on carbon materials, and we compute the associated binding energies. Moreover, analysis of the minimum barrier reaction paths and the associated dissociation barriers of H2 shows the promoting effect of the carbon materials on the dissociation of H2, resulting in barrierless dissociation of H2 on Al4 and Al6 supported on coronene. The effect of graphene is to lower the barrier by up to 0.17 eV with respect to the bare Alncluster, but the dissociation does not become barrierless as on the finite coronene molecule.

Promoting effect of carbon surfaces on H<sub>2</sub> dissociation on Al<sub>n</sub> clusters by first principles calculations

247th National Meeting (2014)

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Promoting effect of carbon surfaces on H2 dissociation on Aln clusters by first principles calculations

Promoting effect of carbon surfaces on H₂ dissociation on Al_n clusters by first principles calculations