全谱拟合法与谢乐公式计算铂纳米晶粒尺寸探讨

采用透射电子显微镜法(TEM)计算燃料电池用Pt/C催化剂中Pt纳米晶粒尺寸是一种常用的精确计算方法,但缺点是成本高,统计结果缺乏代表性,测试复杂。为此,实验制备了一批燃料电池Pt/C催化剂,先采用TEM测定了催化剂中Pt纳米晶粒的平均尺寸,然后分别用谢乐公式和TOPAS软件全谱拟合计算Pt纳米晶粒平均尺寸并与TEM做对比。相对于TEM,通过TOPAS软件全谱拟合计算得到的Pt晶粒平均尺寸的相对误差只有1.3%,即X射线衍射分析技术结合TOPAS软件对Pt纳米晶粒的平均尺寸测试结果与直观的TEM非常接近,实现了Pt纳米晶粒的高效可靠测试。

Discussion on calculation of platinum nanocrystal size by Rietveld refinement and Scherrer formula

The calculation of platinum nanocrystal size in Pt/C catalyst for fuel cell by transmission electron microscopy (TEM) is a commonly used method with good accuracy. However, it has some disadvantages, such as high cost, poor representativeness in statistics, and complex measurement. A batch of Pt/C catalysts for fuel cell were prepared. First, the average size of platinum nanocrystals in the catalyst was measured by TEM. Then, the average size of platinum nanocrystals was calculated by Scherrer formula and Rietveld refinement of TOPAS software, respectively. The calculation results were compared with the TEM method. Compared with TEM method, the relative error of average size of platinum nanocrystals calculated by Rietveld refinement of TOPAS software was only 1.3%. In other words, the measurement results of average size of platinum nanocrystals by X-ray diffraction analysis combined with TOPAS software were very close to those of intuitive TEM method, thus realizing the efficient and reliable measurement of platinum nanocrystals.