Multistep nucleation of nanocrystals in aqueous solution. Nature Chemistry, January 2017.

By N.Duane Loh1,2, Soumyo Sen3, Michel Bosman4,5, Shu Fen Tan6, Jun Zhong1,2, Christian A. Nijhuis6,7, Petr Král3,8, Paul Matsudaira2,9 & Utkur Mirsaidov1,2,7,10

Nature Chemistry. January 2017. 9(1). 77-82. doi: 10.1038/nchem.2618.

Abstract

Schematic: Steps in nucleation

The nucleation and growth of solids from solutions impacts many natural processes and is fundamental to applications in materials engineering and medicine. For a crystalline solid, the nucleus is a nanoscale cluster of ordered atoms that forms through mechanisms still poorly understood. In particular, it is unclear whether a nucleus forms spontaneously from solution via a single- or multiple-step process. Here, using in situ electron microscopy, we show how gold and silver nanocrystals nucleate from supersaturated aqueous solutions in three distinct steps: spinodal decomposition into solute-rich and solute-poor liquid phases, nucleation of amorphous nanoclusters within the metal-rich liquid phase, followed by crystallization of these amorphous clusters. Our ab initio calculations on gold nucleation suggest that these steps might be associated with strong gold-gold atom coupling and water-mediated metastable gold complexes. The understanding of intermediate steps in nuclei formation has important implications for the formation and growth of both crystalline and amorphous materials.

 

1Department of Physics, National University of Singapore, Singapore.
2Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore.
3Department of Chemistry, University of Illinois at Chicago, USA.
4Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research),Singapore.
5Department of Materials Science and Engineering, National University of Singapore, Singapore.
6Department of Chemistry, National University of Singapore, Singapore.
7Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore.
8Department of Physics and Biopharmaceutical Sciences, University of Illinois at Chicago, USA.
9MechanoBiology Institute, National University of Singapore, Singapore.
10NanoCore, National University of Singapore, Singapore.