Qikui's paper has been accepted for publication in Advanced Functional Materials (Impact factor: 13.325). Congratulations!

Authors: Qikui Fan, Kai Liu, Ji Feng, Fumin Wang, Zhaojun Liu,  Moxuan Liu, Yadong Yin, and Chuanbo Gao*

Title: Building High-Density Au-Ag Islands on Au Nanocrystals by Partial Surface Passivation

Link to the Publisher: https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201803199

News reports: XJTU News   8月22日第三版（中国科技网新闻 地方要闻）

Abstract: As an advanced level of control in colloidal synthesis, it is highly desirable to create secondary structures of nanocrystals in a controllable manner for collective properties. Of particular interest is the generation of nanoislands of plasmonic metals (Ag, Au) at a high density around their pre-existing primary nanocrystals, which may produce abundant hotspots for surface-enhanced Raman scattering (SERS). Often such secondary structures are difficult to be achieved by direct crystal growth because a conformal growth is favorable due to the lattice match of these metals. Here we overcome this challenge by developing a partial surface passivation strategy which can effectively shift the crystal growth mode from the “Frank-van der Merwe” mode to the “Volmer-Weber” mode, giving rise to nanoislands as a secondary structure on Au nanocrystals. The key to this strategy is the modification of the Au surface with Ag and subsequent adsorption of iodide at the Ag sites. Further deposition of Au on the modified surface leads to the formation of well-defined Au-Ag alloy islands of a high density on Au nanocrystals, which exhibit excellent SERS activity. This partial surface passivation strategy is fundamentally important and may inspire further endeavors in pursuit of novel secondary nanostructures and intriguing properties.

《科技日报》8月22日第三版报道全文：贵金属纳米岛提升分子检测灵敏度

中国科技网·科技日报（孟祥丽 记者 史俊斌）记者8月20日从西安交通大学获悉,该校前沿科学技术研究院高传博教授课题组利用表面工程策略，成功在金纳米材料的表面制备出高密度的金银合金纳米岛状结构，并因此赋予其优异的表面等离子共振性质和分子检测性能。这一成果发表在最新出版的国际材料领域权威期刊《先进功能材料》上。

在贵金属纳米材料的表面可控构筑亚尺度的结构特征有望为材料带来崭新的特性，成为贵金属纳米结构设计的新思路。通常在单一金属或具有相同晶格常数的金银体系中，晶体生长遵循层状生长模式，不利于亚尺度结构特征的形成。

为克服这一挑战，西安交大研究人员开发了新型的纳米晶体表面工程策略，他们通过在金纳米晶的表面修饰银-卤素化学键，实现了金纳米晶表面的局域钝化，从而有效诱导了纳米晶从层状生长模式到岛状生长模式的转变，在其表面可控构筑了高密度的金银合金纳米岛状结构。该类特殊的表面结构赋予金纳米晶独特的表面等离子共振性质及优异的表面增强拉曼散射活性，在高灵敏度分子检测、生物传感、成像和光催化等领域具有重要的应用价值。