Multistep nucleation of nanocrystals in aqueous solution

• Published in: Nature chemistry Vol. 9; no. 1; pp. 77 - 82
• Main Authors: Loh, N. Duane, Sen, Soumyo, Bosman, Michel, Tan, Shu Fen, Zhong, Jun, Nijhuis, Christian A., Král, Petr, Matsudaira, Paul, Mirsaidov, Utkur
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2017; Nature Publishing Group
• Subjects: 147/137; 147/143; 639/638/549/2263; 639/925/357/354; Analytical Chemistry; Biochemistry; Chemistry; Chemistry/Food Science; Crystallization; Gold; Inorganic Chemistry; Materials engineering; Nanocrystals; Nucleation; Organic Chemistry; Physical Chemistry; Silver
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.2618

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. Crystals grow from nuclei. In systems where nuclei are nanometre-sized and form quickly, it is difficult to determine the mechanism of their formation. Now, through in situ TEM, the demixing of a supersaturated aqueous gold solution into metastable gold-poor and gold-rich liquid phases is observed, the latter yielding stable clusters that become nuclei for nanocrystal growth.