title: Hydrogen Spillover between Single Gold Nanorods and Metal Oxide Supports: A Surface Plasmon Spectroscopy Study.
abstract: We used dark field spectroscopy to monitor the dissociation of hydrogen on single gold nanoparticles embedded in metal oxide supports. Individual gold nanorods were monitored in real time to reveal the peak position, the full width at half-maximum, and the relative intensity of the surface plasmon resonances during repeated N2-H2-N2 and air-H2-air cycles. Shifts in the spectra are shown to be due to changes in electron density and not to refractive index shifts in the environment. We demonstrate that hydrogen does not dissociate on gold nanorods (13 nm × 40 nm) at room temperature when in contact with silica and that electrons or hydrogen atoms migrate from Pt nanoparticles to Au nanoparticles through the supporting metal oxide at room temperature. However, this spillover mechanism only occurs for semiconducting oxides (anatase TiO2 and ZnO) and does not occur for Au and Pt nanoparticles embedded in silica. Finally, we show that hydrogen does dissociate directly on anatase surfaces at room temperature during air-H2-air cycles. Our results show that hydrogen spillover, surface dissociation of reactants, and surface migration of chemical intermediates can be detected and monitored in real time at the single particle level.
authors.affiliation: School of Chemistry & Bio21 Institute, University of Melbourne , Parkville, VIC 3010, Australia.
authors.forename: Sean S E
authors.initials: SS
authors.lastname: Collins
authors.affiliation: INSTM and Dipartimento di Ingegneria Industriale, Università di Padova , Via Marzolo 9, 35131 Padova, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Cittadini
authors.affiliation: Instituto de Ciencia de Materiales de Madrid (CSIC) , C/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Pecharromán
authors.affiliation: INSTM and Dipartimento di Ingegneria Industriale, Università di Padova , Via Marzolo 9, 35131 Padova, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Martucci
authors.affiliation: School of Chemistry & Bio21 Institute, University of Melbourne , Parkville, VIC 3010, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Mulvaney
keywords: catalysis support effect; gas sensing; hydrogen adsorption; spillover; surface plasmon spectroscopy; thin films