Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India.
J Colloid Interface Sci. 2012 Jan 1;365(1):117-21. doi: 10.1016/j.jcis.2011.09.005. Epub 2011 Sep 10.
In order to examine the applicability of the diffusion-limited Ostwald ripening model to the growth kinetics of nanocrystals, platinum nanocrystals prepared by two different methods have been investigated by a combined use of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). One of the methods of synthesis involved the reduction of chloroplatinic acid by sodium citrate while in the other method reduction was carried out in the presence of polyvinylpyrrolidone (PVP) as a capping agent. The growth of platinum nanocrystals prepared by citrate reduction in the absence of any capping agent follows a Ostwald ripening growth with a D(3) dependence. In the presence of PVP, the growth of platinum nanocrystals does not completely follow the Ostwald ripening model, making it necessary to include a surface reaction term in the growth equation. Thus, the growth of platinum nanocrystals in the presence of PVP has contributions both from diffusion and surface reaction, exhibiting a D(3)+D(2) type behavior.
为了检验扩散限制奥斯特瓦尔德熟化模型在纳米晶体生长动力学中的适用性，我们综合使用小角 X 射线散射（SAXS）和透射电子显微镜（TEM）研究了通过两种不同方法制备的铂纳米晶体。其中一种合成方法涉及用柠檬酸钠还原氯铂酸，而在另一种方法中，在作为封端剂的聚乙烯吡咯烷酮（PVP）的存在下进行还原。在没有任何封端剂的柠檬酸钠还原制备的铂纳米晶体的生长遵循奥斯特瓦尔德熟化生长，具有 D(3)依赖性。在 PVP 的存在下，铂纳米晶体的生长并不完全遵循奥斯特瓦尔德熟化模型，因此需要在生长方程中包含表面反应项。因此，在 PVP 的存在下，铂纳米晶体的生长既来自扩散，也来自表面反应，表现出 D(3)+D(2)型行为。
