Hydrogen spillover on a carbon supported platinum fuel cell catalyst: A computational and inelastic neutron scattering study

We are undertaking a study of hydrogen spillover using neutron scattering techniques allied with computer modelling. We report the direct observation of spillover hydrogen on a Pt/C fuel cell catalyst and a computational model of the interaction of spillover hydrogen with the catalyst support. Dihydrogen molecules dissociate on the Pt component of the catalyst and H atoms spillover onto the carbon support. The spillover H atoms comprise a mobile phase on the surface of the carbon characterised by a broad inelastic neutron scattering spectrum. A quantum mechanical calculation of the interaction energy of H atoms with the carbon surface shows that the energy differences between different potential binding sites are no more than a few kJ. Thus the spillover hydrogen is in the form of a layer on the carbon of weakly bound, mobile H atoms.