Size Classification of Au Nanometer-sized Particles by DMA and Their Application as a Catalyst

采用蒸发-冷凝法制备了金纳米颗粒，并用差分迁移率分析仪（DMA）测量了其粒径分布。将Au粒子产生温度从1000℃提高到1100℃，实验证实可以生成尺寸为1.7 ~ 3.5 nm的Au粒子。将TEM观测所得的平均粒径D_<m，TEM>与DMA靶粒径D_<DMA>进行比较，得到了较好的相关性。因此，我们得出结论，我们的DMA系统可用于纳米级颗粒的分类。在作为催化剂的应用中，我们证实了金纳米颗粒的生成，其尺寸在1.7 - 10纳米之间，可能具有较高的催化活性。随着炉温的降低，颗粒的浓度降低，但颗粒的粒度分布可以通过改变炉温来控制。通过透射电镜观察，发现金颗粒的形貌不是球形的。为了生成球形的金纳米粒子，我们在粒子发生器出口和气溶胶增压器之间安装了加热炉，实验证实，通过这种处理，尺寸为4.3 nm的金纳米粒子的形状趋于球形。目前正在研究以这种方法处理的金纳米级颗粒的催化性能。

Au nanometer-sized particles were generated by evaporation-condensation method, and their particles size distributions were measured by a Differential Mobility Analyzer (DMA) system. As a result of raising the Au particles generator temperature from 1000 to 1100 ℃, the generation of Au particles with 1.7 nm to 3.5 nm in size was experimentally confirmed. Good correlation was obtained when we compared the mean diameter D_<m,TEM> which was calculated from the TEM observation of particles with the D_<DMA> which was DMA targeted size. Consequently, we concluded that our DMA system was available to classification of the nanometer-sized particles. As application as a catalyst, we confirmed the generation of Au nanometer-sized particles ranging from 1.7 to 10 nanometers in size which might show high catalytic activity. The size distribution of these particles was controlled by changing the furnace temperature, although the particle concentration decreased with the decrease in the furnace temperature. The morphology of Au particles was found to be not spherical from the TEM observation. In order to generate the spherical Au nanoparticles, we installed reheating furnace between the outlet of particle generator and the aerosol charger, It was experimentally confirmed that shape of Au particles with 4.3 nm in size tended to be sphere by this processing. The catalytic performance of thus treated Au nanometer size-selected particles are now under way.