School of Chemistry & Bio21 Institute, University of Melbourne , Parkville, VIC 3010, Australia.
INSTM and Dipartimento di Ingegneria Industriale, Università di Padova , Via Marzolo 9, 35131 Padova, Italy.
ACS Nano. 2015 Aug 25;9(8):7846-56. doi: 10.1021/acsnano.5b02970. Epub 2015 Jul 20.
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.
我们使用暗场光谱学来监测嵌入在金属氧化物载体中的单个金纳米粒子上的氢的离解。实时监测单个金纳米棒，以揭示表面等离子体共振的峰值位置、半峰全宽和相对强度，在重复的 N2-H2-N2 和空气-H2-空气循环过程中。光谱的位移表明是由于电子密度的变化，而不是环境折射率的变化。我们证明，当金纳米棒（13nm×40nm）与二氧化硅接触时，在室温下不会发生氢解离，并且电子或氢原子会通过支撑的金属氧化物从 Pt 纳米粒子迁移到 Au 纳米粒子。然而，这种溢流机制仅发生在半导体氧化物（锐钛矿 TiO2 和 ZnO）上，而不会发生在嵌入二氧化硅中的 Au 和 Pt 纳米粒子上。最后，我们表明，在空气-H2-空气循环过程中，氢在室温下直接在锐钛矿表面上离解。我们的结果表明，可以在单粒子水平上实时检测和监测氢溢流、反应物的表面离解以及化学中间体的表面迁移。
