We present an ab initio molecular dynamics study on the adsorption of hydrogen atoms and phenol molecules on a Pt50 nanoparticle supported on a graphene sheet. Coverage effects on hydrogen and phenol adsorption energies were initially investigated. It was found that, with respect to gas phase H2, hydrogen adsorption energy per H atom is about -58/-48 kJ/mol (with/without a phenol molecule bound to Pt50) when the nanoparticle is covered with 25, or 50, H atoms. The hydrogen coverage effect on phenol adsorption is however strong. The adsorption energy of a phenol molecule on a Pt50 particle with bound H atoms is as large as -304 kJ/mol. Nevertheless, the phenol adsorption energy decreased to -136 and +11 kJ/mol on a Pt50 particle covered with 25 and 50 H atoms, respectively. We then looked at the distribution of adsorption sites of H atoms on the particles. In the system of 25 H atoms on Pt50, H atoms bind to Pt atoms mostly in the bridge adsorption sites (~74 %), then in the on-top sites (~25 %), and some in the hollow sites (~1%). In the system of 50 H atoms on Pt50, the population of H atoms in the bridge sites is ~67%, on-top sites ~30%, and hollow sites ~3%. Importantly, adsorbed H atoms clearly change Pt-Pt distances in the nanoparticle. Dynamical, geometric, electronic properties of these systems, and the competitive adsorption of H atoms and phenol molecules will also be addressed.

Binding of hydrogen and phenol at a Pt50 nanoparticle supported on graphene: Ab initio molecular dynamics simulations

255th National Meeting (2018)

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