ICC: Size and Structure Sensitivity of Metal Nanoparticle Reactivity in the Aerosol State

我们建议研究气溶胶状态下小的催化相关分子--例如氧、氢、一氧化碳和简单的不饱和碳氢化合物--在无载体的金颗粒上的吸收和反应。金颗粒将在炉中蒸发生产，或通过适当的金属有机前体的热分解来生产。要解决的具体问题是：吸附和解吸动力学，如通过测量粘着概率和热解吸速率揭示的。这些实验将利用罗伯茨实验室开发的一种仪器，该仪器将电迁移率的变化与亚单层材料的吸收和损失联系起来。使用Kasper开发的一种仪器，利用气溶胶光电子能谱(APES)研究大气压条件下金属气溶胶纳米颗粒的催化活性，揭示了多相反应路径。这些实验将由新一代粒子电迁移率分析仪实现，该分析仪可以产生选定直径为1.5 nm的单分散流，该尺寸通常被认为是分子簇和粒子之间的边界。

We propose to study the uptake and reaction of small, catalytically relevant molecules- e.g., oxygen, hydrogen, carbon monoxide, and simple unsaturated hydrocarbons- onto unsupported gold particles in the aerosol state. The gold particles will be produced evaporatively in a furnace or by thermal decomposition of a suitable metal organic precursor. Specific issues to be addressed are:Adsorption and desorption kinetics, as revealed by measurements of sticking probabilities and thermal desorption rates. These experiments will make use of an instrument developed in Roberts’ laboratory that relates changes in electric mobility to uptake and loss of sub-monolayer quantities of material.Detailed heterogeneous reaction pathways, using an instrument developed by Kasper in which aerosol photoemission spectroscopy (APES) is used to study catalytic activity in metal aerosol nanoparticles under atmospheric pressure conditions.Size-dependent effects. These experiments will be enabled by a new generation of particle electric mobility analyzers that can create monodisperse streams of selected diameter as small as 1.5 nm, a size usually considered to be the border between molecular clusters and particles.