Multistep nucleation of nanocrystals in aqueous solution


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.

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Figure 1: Proposed three-step pathway for gold and silver nucleation in solution.
Figure 2: Amorphous gold nanoclusters appear from gold-rich spinodal structures.
Figure 3: Crystallinities of 74 gold nanoclusters that emerged from gold-rich phases.
Figure 4: Calculations of ground-state energies for a hydrated pair of gold atoms.


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This work was supported by the Singapore National Research Foundation's Competitive Research Program funding (NRF-CRP9-2011-04) and the Young Investigator Award (NUSYIA-FY14-P17) from the National University of Singapore. C.A.N. and M.B. acknowledge support from grant No. NRF-CRP8-2011-07, U.M. and P.M. acknowledges support from the Microbiology Institute (Singapore) and the Centre for Bioimaging Sciences. N.D.L. thanks the support of the Lee Kuan Yew Endowment Fund, and National University of Singapore internal grant No. 154-000-606-112. The work of P.K. was supported by the National Science Foundation Division of Materials Research Grant No. 1309765 and by the American Chemical Society Petroleum Research Funding Grant No. 53062-ND6.

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U.M. and P.M. conceived the study. U.M. designed the in situ experiments, which he performed together with M.B. and S.F.T.; N.D.L. designed and implemented the image processing and statistical analysis on the TEM images, with help from J.Z. and input from U.M., P.M., C.A.N. and M.B.; N.D.L. did and, with U.M. and M.B., wrote up the analyses in the Supplementary Information on CNT, spinodal decomposition and the effects of the electron beam. S.S. and P.K. carried out the hybrid molecular dynamics calculations. N.D.L., C.A.N., P.K., P.M. and U.M. wrote the manuscript from discussions that arose from all authors.

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Correspondence to Christian A. Nijhuis or Petr Král or Utkur Mirsaidov.

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The authors declare no competing financial interests.

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Loh, N., Sen, S., Bosman, M. et al. Multistep nucleation of nanocrystals in aqueous solution. Nature Chem 9, 77–82 (2017).

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