Our paper has been accpeted by Chem (Impact Factor: 14.104), a new flagship chemistry journal published by Cell Press. This work was a collaboration with Prof. Yadong Yin at University of California, Riverside, and Dr. Guoqing at Hokkaido University. Congratulations!

Title: Island growth in the seed-mediated overgrowth of monometallic colloidal nanostructures

Authors: Guoqing Wang, Yiding Liu, Chuanbo Gao*, Lei Guo, Miaofang Chi, Kuniharu Ijiro, Mizuo Maeda, Yadong Yin*

Link to the Publisher: http://www.sciencedirect.com/science/article/pii/S2451929417303510

Abstract: Manipulating growth mode of colloidal nanocrystals is of both fundamental interest and technological importance because it often connects to the control of their shape, morphology and physicochemical properties. In the conventional wisdom, island growth during thin film deposition is restricted to lattice-mismatched materials. Here we show deposition of Au on Au nanostructures (e.g., nanoplates, nanorods and nanospheres) can produce separate Au islands on the seed surface with tunable size and density, while preserving the original crystal structure. The unprecedented island growth in the systems is ascribed to the synergistic effect of fast redox kinetics and surface capping of large polymeric ligands. By decreasing the reaction rate or changing the capping ligands, the deposition of Au on Au nanostructures could be readily transformed from island growth to layer-by-layer mode. We further take advantage of the dense hotspots of the islands-on-plate nanostructures and demonstrate their excellence in surface-enhanced Raman scattering (SERS) detection. 

The Bigger Picture: Noble metal nanocrystals find broad applications in sensing, imaging and catalysis, with their performance heavily dependent on the nanostructures. Till now, general rules of the crystal growth have been established, which constitute the current wisdom in the structural design of noble metal nanocrystals. For example, islands growth of a metal on nanocrystals of another metal is usually induced by lattice mismatch of the two metals. However, in many cases, great possibilities lie beyond these rules for discovering new nanostructures with intriguing properties and applications. Here, we demonstrate this possibility by establishing a new mechanism that allows an unusual island growth mode of monometallic Au without involving any lattice mismatch. It enables production of a family of Au island structures, which showed superior performance in surface-enhanced Raman scattering. Our findings thus is indicative and may inspire further efforts in building sophisticated metal nanostructures.