Fabrication of 2D Au Nanorings with Pt Framework

Transcription

1 Supporting Information Fabrication of 2D Au Nanorings with Pt Framework Hee-Jeong Jang, Songyi Ham, Jesus A. I. Acapulco Jr., Yookyung Song, Soonchang Hong, Kevin L. Shuford,*, and Sungho Park*, Department of Chemistry and Department of Energy Science, Sungkyunkwan University, Suwon , South Korea Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States Figure S1. FESEM images and photographs of the resultant product from the same experiments by using 0.1 M of aqua regia (A, B) and 0.1 M of KI/I 2 solution (C, D) as an Au etchant instead of HAuCl 4 solution. (A) In the case of aqua regia, the harsh oxidative environment induces the dissolution and aggregation of the Pt nanoframes, resulting in the regrowth of nanoparticles having totally different shapes. (D) In the case of KI/I 2 solution, the significant amount of unwanted precipitation exists in the resultant solution after centrifuge. However, the similar shape of Pt@Au nanorings was obtained after several times of purification. S1

2 Figure S2. EDS line mapping of Pt nanoframes. The red line represents the amount of Pt, and the black line is that of Au. The mapping was obtained along the purple line in inset. Please note that the complete removal of Au was not feasible because we used HAuCl 4 solution as an etchant. Figure S3. Crystallinity of Au@Pt nanodisks and Pt@Au nanorings. X-ray diffraction (XRD) patterns of Au@Pt nanodisks (black line), and Pt@Au nanorings (red line). The indicated facet information is the crystallinity of face-centered cubic Au. S2

3 Figure S4. Photograph of the solutions of Au nanodisks, nanodisks, Pt nanoframes, and nanorings. 15 M, 30 M, 60 M, and 120 M of HAuCl 4 were added in each reaction solution for Pt@Au Ring 1-4 during etching process, respectively. Figure S5. Plasmon modes for pure Au nanorings. A) Computed spectra for various orientations that contribute to the average spectrum displayed in Fig. 3B (green trace). There are two in-plane modes (incident electric field parallel to the ring plane; labeled Au-E in ) and one out of plane mode (incident electric field perpendicular to the ring plane; labeled Au-E out ). Also shown are contour plots of the electric field enhancement (E 2 / E 0 2 ), where the wavelength and the direction of E and k are denoted. The planes displayed bisect the nanoparticle. Panels B, C, and D correspond to out of plane dipole, in-plane dipole, and in-plane quadrupole modes, respectively. S3

4 Figure S6. Plasmon modes for nanorings. A) Computed spectra for various orientations that contribute to the average spectrum displayed in Fig. 3B (red trace). There is one in-plane mode (incident electric field parallel to the ring plane; labeled in ) and one out of plane mode (incident electric field perpendicular to the ring plane; labeled Pt@Au-E out ). Also shown are contour plots of the electric field enhancement (E 2 / E 0 2 ), where the wavelength and the direction of E and k are denoted. The planes displayed bisect the nanoparticle. Panels B and C correspond to out of plane dipole and in-plane dipole modes, respectively. Note the core/shell structure damps the in-plane excitation (compared to pure Au nanorings), leading to a less well-defined dipole, near field pattern. Coupling between the Au and Pt portions of the nanoring are evident. S4

5 Figure S7. FESEM images of Au nanodisks (A), nanoprisms (B), and hexagonal nanoplates (C). Each Au nanoplate is used as a template for Pt@Au circular, triangular, and hexagonal nanorings (Fig. 5). (D) UV-vis-NIR spectra of Au nanodisks, nanoprisms, and hexagonal nanoplates. Figure S8. FESEM images of Au nanosphere (A), nanorods (B), and nanodisks (C). Each Au nanoparticle is utilized for the measurement of the dielectric sensitivity (Fig. 6A-C and Table S1). S5

6 Table S1. Representative LSPR properties of Au nanoparticles and nanorings. Au nanospheres (Fig. 6A), Au nanorods (Fig. 6B), Au nanodisks (Fig. 6C), and nanorings (Fig. 6D). (T : transverse mode ; L : longitudinal mode ; Out : out-of-plane mode ; In : in-plane mode) S6