Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009

Supplementary Information

Evolution of gold nanoparticles through Catalan, Archimedean, and Platonic solids Do Youb Kim,†a Sang Hyuk Im,*†b O Ok Park*a and Yong Taik Limc

a

Department of Chemical and Biomolecular Engineering (BK21 graduate program), Korea Advanced

Institute of Science and Technology (KAIST), 335 Gwahangno, Yuseong-gu, Daejeon, 305-701 b

KRICT-EPFL Global Research Laboratory, Advanced Materials Division, Korea Research Institute of

Chemical Technology, 19 Singsungno, Yuseong-gu, Daejeon 305-600 c

Korea Research Institute of Bioscience and Biotechnology (KRIBB), 111 Gwahangno, Yuseong-gu,

Daejeon 305-806

*

To whom correspondence should be addressed.

E-mail: [email protected], [email protected] † These two authors equally contributed to this work.

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Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009

Figure S1. SEM images of gold nanoparticles with concentration of PVP(3.5 mL DMF and 1.4 mL of water are added to 0.1 mL of 94.2 mM HAuCl4 with 7 mL of x mM PVP in DMF). X= (a) 0.10 mM, (b) 0.21 mM, (c) 1.04 mM, (d) 1.46 mM, (e) 1.88 mM, and (f) 2.19 mM.

Fig. S1 shows the SEM images of produced gold nanoparticles with concentration of PVP. These figures clearly show that the concentration of PVP plays a critical role to determine shape, size and monodispersity of produced gold nanoparticles. Especially we could not obtain uniform gold 2

Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009 nanoparticles in shape and size below the concentration of HAuCl4 of ~1.46 mM because of the deficient concentration of PVP to sufficiently stabilize the gold nanoparticles. However, over the concentration of HAuCl4 of 1.46 mM the produced gold nanoparticles seem to be sufficiently stabilized and lead the uniform octahedral particles. Moreover, basically the shape is not changed over 1.46mM concentration except that the edge becomes dull. This might be explained by that the PVP stabilizes {111} facet of gold nanoparticles over the concentration of HAuCl4 of 1.46 mM. Note that PVP can play an important role to control the shape and monodispersity of gold nanoparticles but it cannot produce such shape controlled uniform gold nanoparticles by itself without cooperation of water. Fig. S2 shows the SEM images of generated gold nanoparticles with variation of water under the same concentration of PVP(1.46 mM). Fig. S2a shows the case in which no water was added. In the absence of water, the rate of formation of the gold nanoparticles is the slowest because of the low concentration of Au(III) ions, which possibly form due to the very small amount of water present in DMF. The resulting particles were found to consist of a mixture of rhombic dodecahedra with sharp edges and irregular particles with a diameter of ~ 300 nm since only a few nucleated seed particles increase in size due to the lack of water. This clearly shows that PVP cannot produce the shape controlled uniform particles by itself in our experimental condition. Fig. S2b shows the case in which 0.5 mL of water was added. The gold nanoparticles nucleate more quickly and form monodisperse truncated rhombic dodecahedra with a diameter of ~ 180 nm because the dissociated Au(III) ions are readily reduced into gold atoms, forming nucleated seeds, and then nanoparticles are produced by further growth. In addition, the multiply twinned and irregular particles are further reduced by the addition of water, which implies that the twinned seeds formed at early stages are etched away by the backward oxidative etching reaction. This provides clear evidence that the concentration of water plays more a critical role to determine the shape of produced gold nanoparticles in our experimental condition. Further addition of water can also change the shapes of produced gold nanoparticles. The addition of 1.4 mL and 2 mL water produced octahedral and truncated octahedral nanoparticles through different transformation pathway, respectively (see the main text). These results clearly show that the concentration of water is 3

Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009 more dominant factor to control the shape of gold nanoparticles than that of PVP in our experimental condition because the concentration of water is related to the solubility of HAuCl4, forward reaction rate, backward oxidative etching reaction and so on. Conclusively the shape and uniformity can be controlled by the cooperation of PVP and water in our experimental condition and especially on/over the concentration of PVP of 1.46 mM, the shape of produced gold nanoparticles can be controlled dominantly by the concentration of water.

Figure S2. SEM images of produced gold nanoparticles with amounts of added water(4.9-x mL DMF and x mL of water are added to 0.1 mL of 94.2 mM HAuCl4 with 7 mL of 1.46 mM PVP in DMF). x is (a) 0 mL and (b) 0.5 mL.

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Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009

(a) Rhombic dodecahedron

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Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009

(b) Rhombicuboctahedron

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Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009

(c) Octahedron

Figure S3. Additional SEM, TEM images and ideal models of (a) rhombic dodecahedron, (b) rhombicubocahedron, and (c) octahedron. Fig. S3 displays additional SEM and TEM images to confirm the shape transformation of gold nanoparticles with the reaction time. These images provide sufficient evidence to confirm the shape and

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Supplementary Material for CrystEngComm This journal is (c) The Royal Society of Chemistry 2009 structure of the produced particles. See the following references to compare and recognize the structure and shape of the particles.1,2

References 1

G. H. Jeong, M. Kim, Y. W. Lee, W. Choi, W. T. Oh, Q.-H. Park, S. W. Han, J. Am. Chem. Soc.,

2009, 131, 1672. 2

W. Niu, S. Zheng, D. Wang, X. Liu, H. Li, S. Han, J. Chen, Z. Tang, G. Xu, J. Am. Chem. Soc.,

2009, 131, 697.

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