Tingting's recent work on encapsulation of ultrasmall Au nanoparticles for high-temperature catalysis has been published in ACS Nano. Congratulations!

Title: Unconventional Route to Encapsulated Ultrasmall Gold Nanoparticles for High-Temperature Catalysis

Authors: Zhang, T,; Zhao, H.; He, S.;Liu, K,; Liu, H.;* Yin, Y.;* Gao, C.*

Link to Publisher: http://pubs.acs.org/doi/abs/10.1021/nn502349k.

Highlight by XJTU: http://news.xjtu.edu.cn/info/1004/43140.htm

Abstract: Ultra-small gold nanoparticles (us-AuNPs, < 3 nm) have been recently recognized as surprisingly active and extraordinarily effective green catalysts. Their stability against sintering during reactions however remains a serious issue for practical applications. Encapsulating such small nanoparticles in a layer of porous silica can dramatically enhance the stability, but it has been extremely difficult to achieve using conventional sol-gel coating methods due to the weak metal/oxide affinity. In this work, we address this challenge by developing an effective protocol for the synthesis of us-AuNP@SiO2 single-core/shell nanospheres. More specifically, we take an alternative route by starting with ultra-small gold hydroxide nanoparticles, which have excellent affinity to silica, then carrying out controllable silica coating in reverse micelles, and finally converting gold hydroxide particles into well-protected us-AuNPs. With a single-core/shell configuration that prevents sintering of nearby us-AuNPs and amino group modification of the Au/SiO2 interface that provides additional coordinating interactions, the resulting us-AuNP@SiO2 nanospheres are highly stable at high temperatures, and show high activity in catalytic CO oxidation reactions. A dramatic and continuous increase in the catalytic activity has been observed when the size of the us-AuNPs decreases from 2.3 nm to 1.5 nm, which reflects the intrinsic size effect of the Au nanoparticles on an inert support. The synthesis scheme described in this work is believed to be extendable to many other ultra-small metal@oxide nanostructures for much broader catalytic applications.

中文简介：

粒径小于3 nm的金纳米粒子由于尺寸效应而具有优异的催化活性，但是它们极易发生粒子间的团聚或烧结现象从而失去活性，在中高温催化反应中尤为显著。在本文中，作者提出了一种新颖的二氧化硅包覆方法，借助氢氧化金中间体克服了长期以来小尺寸金属纳米粒子难以包覆金属氧化物的困难，得到了金/二氧化硅核壳结构的纳米材料，从而实现了对小尺寸金纳米粒子的稳定化。该材料表现出优良的高温稳定性及对一氧化碳氧化等反应的催化活性。本文提出的合成策略也对其它金属纳米催化剂的制备提供了新的思路。

 该论文是在与中科院沈阳金属研究所刘洪阳博士和美国加州大学河滨分校殷亚东博士的合作下完成的，论文发表在纳米材料领域权威期刊ACS Nano（影响因子：13.334）上。