Volume 3, Issue 4, Pages 678-690 (October 2017) Island Growth in the Seed-Mediated Overgrowth of Monometallic Colloidal Nanostructures  Guoqing Wang, Yiding Liu, Chuanbo Gao, Lei Guo, Miaofang Chi, Kuniharu Ijiro, Mizuo Maeda, Yadong Yin  Chem  Volume 3, Issue 4, Pages 678-690 (October 2017) DOI: 10.1016/j.chempr.2017.08.004 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Shift of Island Growth on Au Nanoplates to Layer-By-Layer Mode by Manipulation of Reaction Kinetics The TEM, SEM, and AFM images (left to right) in (A) reveal the original surfaces of two-dimensional Au nanoplates to be smooth. Overgrowth of the Au nanoplates produces islands on the nanoplates at a relatively high reaction kinetics (B), whereas island deposition (B–D) is gradually transformed to layer-by-layer growth (E) when reaction kinetics are decreased, as demonstrated by TEM, SEM, and AFM analyses (top to bottom). All AFM images are 1.5 × 1.5 μm in area. The color scales indicate the height values. The amount of Au precursor was fixed. See also Figures S1–S7 and S12 and Table S1. Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Layer-By-Layer and Island Growth on the Au Surface Manipulated by Surface Capping Ligand TEM images of CTAB-capped Au nanoplates (A) and nanorods (D) and their grown nanostructures (B and E, respectively). The grown nanostructures of PVP-exchanged Au nanoplates (C) and Au nanorod (F) are shown for comparison. The growth conditions were kept identical to those in Figure 1B. See also Figures S8–S12. Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Monitoring the Island Growth on Au Nanoplates (A and B) UV-visible-NIR extinction spectra (A) and representative TEM (top) and SEM (bottom) images (B) of the Au nanoplates after different periods of growth. (C) Evolution of island size and gap distance as a function of growth time. Error bars indicate the standard deviations. See also Figures S13−S17 and Table S2. Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 Characterization of the Crystalline Structure of a Au Nanoplate after Island Deposition (A and B) A typical TEM image (A) of an overgrown Au nanoplate after reaction for 30 min and the corresponding SAED pattern (B). (C) High-resolution TEM image of islands in the area of the overgrown Au nanoplate shown in (A). The insert shows the corresponding fast Fourier transform image. See also Figures S15 and S16. Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 Electromagnetic Field Enhancement Effect and SERS Activity of Au Nanoplates after Islands Were Grown for Different Lengths of Time (A) Calculated localized electromagnetic field distributions of Au nanoplates with different island sizes under the excitation of a plane wave (wavelength, 633 nm). The color scale represents lg(E2/E02), where E and E0 are the amplitudes of the local and incident electromagnetic fields, respectively. The island diameter (d) and gap distance (g) refer to the results shown in Table S2. (B) SERS spectra of crystal violet adsorbed on Au nanoplates deposited on a silicon substrate. (C) Plots of Raman intensity at 1,620 cm−1 as a function of island growth time. The error bars refer to the standard deviations from three independent measurements at different areas. (D) SERS spectra of crystal violet adsorbed on a single particle (sub-monolayer) of Au nanoplate before and after the island growth for 30 and 60 min, respectively. Inset: high-magnification SEM image (scale bar: 100 nm) of the corresponding particle subjected to single-particle SERS. (E) The corresponding single nanoplate subjected to SERS analysis was imaged by SEM (left) and the optical microscope equipped on the Raman spectrophotometer (right), as indicated by arrows. Note that a sub-monolayer of the pristine nanoplate was deposited for SERS analysis near an artificial mark because of the difficulty in optical observation of single pristine nanoplates. See also Figures S18−S20. Chem 2017 3, 678-690DOI: (10.1016/j.chempr.2017.08.004) Copyright © 2017 Elsevier Inc. Terms and Conditions