Nanoscale mixing during double-flame spray synthesis of heterostructured nanoparticles
Nanoscale mixing during double-flame spray synthesis of heterostructured nanoparticles
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DOI：
10.1007/s11051-015-2975-8
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发表时间：
2015-04-08
影响因子：
2.5
通讯作者：
Maedler, L.
中科院分区：
文献类型：
--
作者：
Grossmann, H. K.;Grieb, T.;Maedler, L.
将两个纳米颗粒产生火焰反应器与双火焰（DF）喷雾热解工艺相结合，是多化合物材料和异质结构的高温气相合成的一种有吸引力的方法。它允许单独控制各个火焰中的颗粒生长，直至形成异质结构的交叉点或混合点。以 TiO2 上的 Pt 为例，研究了气溶胶流混合对工艺温度和产品特性的影响。通过傅里叶变换红外光谱和热电偶测量以及计算流体动力学确定温度，同时根据表面积、Pt 色散测量和透射电子显微镜图像分析研究混合程度。样方法结合变异系数用于量化 TiO2 载体上 Pt 簇分布的均匀性。对于两个火焰射流的大交叉距离和小交叉角，观察到化合物的不均匀混合和大 Pt 颗粒的形成。对于小交叉距离和大角度，实现了均匀的 Pt 分布。基于这些发现，建立了可以转移到其他材料系统的工艺设计规则。
The combination of two nanoparticle-producing flame reactors to a double-flame (DF) spray pyrolysis process is an attractive method for the high-temperature gas-phase synthesis of multicompound materials and heterostructures. It allows separate control of particle growth in the individual flames up to the intersection or mixing point where the formation of heterostructures takes place. The effect of mixing of the aerosol streams on the process temperature and product characteristics is investigated based on the example of Pt on TiO2. Temperatures were determined by Fourier-transform infrared spectroscopy and thermocouple measurements along with computational fluid dynamics, while the degree of mixing was investigated based on surface area, Pt-dispersion measurements, and transmission electron microscopy image analyses. The quadrat method in combination with the variation coefficient was used to quantify the uniformity of the Pt cluster distribution on the TiO2 support. For high intersection distances of the two flame jets and small intersection angles, nonuniform mixing of the compounds and the formation of large Pt particles are observed. For small intersection distances and large angles, a uniform Pt distribution was achieved. Based on these findings, process design rules were established which can be transferred to other material systems.