| Autor: |
Lindley SA; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States., Cooper JK; Chemical Sciences Division, Joint Center for Artificial Photosynthesis , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States., Rojas-Andrade MD; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States., Fung V; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States., Leahy CJ; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States., Chen S; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States., Zhang JZ; Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States. |
| Abstrakt: |
In principle, the diameter and surface plasmon resonance (SPR) frequency of hollow metal nanostructures can be independently adjusted, allowing the formation of targeted photoactivated structures of specific size and optical functionality. Although tunable SPRs have been reported for various systems, the shift in SPR is usually concomitant with a change in particle size. As such, more advanced tunability, including constant diameter with varying SPR or constant SPR with varying diameter, has not been properly achieved experimentally. Herein, we demonstrate this advanced tunability with hollow gold nanospheres (HGNs). HGNs were synthesized through galvanic exchange using cobalt-based nanoparticles (NPs) as sacrificial scaffolds. Co 2 B NP scaffolds were prepared by sodium borohydride nucleation of aqueous cobalt chloride and characterized using UV-vis, dynamic light scattering, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Careful control over the size of the Co 2 B scaffold and its galvanic conversion is essential to realize fine control of the resultant HGN diameter and shell thickness. In pursuit of size control, we introduce B(OH) 4 - (the final product of NaBH 4 hydrolysis) as a growth agent to obtain hydrodynamic diameters ranging from ∼17-85 nm with relative standard deviation <3%. The highly monodisperse Co 2 B NPs were then used as scaffolds for the formation of HGNs. In controlling HGN shell thickness and uniformity, environmental oxygen was shown to affect both the structural and optical properties of the resultant gold shells. With careful control of these key factors, we demonstrate an HGN synthesis that enables independent variation of diameter and shell thickness, and thereby SPR, with unprecedented uniformity. The new synthesis method creates a truly tunable plasmonic nanostructure platform highly desirable for a wide range of applications, including sensing, catalysis, and photothermal therapy. |
