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

我们建议研究小的催化相关分子的吸收和反应-例如，氧气、氢气、一氧化碳和简单的不饱和烃--在气溶胶状态下附着在无支撑的金颗粒上。金颗粒将在炉中蒸发产生或通过合适的金属有机前体的热分解产生。要解决的具体问题是：吸附和解吸动力学，所揭示的粘附概率和热解吸率的测量。这些实验将利用Roberts实验室开发的一种仪器，该仪器将电迁移率的变化与材料的亚单层数量的吸收和损失联系起来。详细的非均相反应途径，使用Kasper开发的仪器，其中气溶胶光电子能谱（APES）用于研究大气压条件下金属气溶胶纳米颗粒的催化活性。这些实验将通过新一代粒子电迁移率分析仪实现，该分析仪可以创建选定直径小至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.