期刊
NANO LETTERS
卷 20, 期 1, 页码 192-200出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b03588
关键词
Metal nanostructures; gold triangular nanoprisms; localized surface plasmon resonance; plasmon electron density; plasmoelectric effect; work function; spectral reversibility
类别
资金
- National Science Foundation [CBET-1604617]
Ligand-controlled tuning of localized surface plasmon resonance (LSPR) properties of noble metal nanostructures is fundamentally important for various optoelectronic applications such as photocatalysis, photovoltaics, and sensing. Here we demonstrate that the free carrier concentration of gold triangular nanoprisms (Au TNPs) can be tuned up to 12% upon functionalization of their surface with different para-substituted thiophenolate (X-Ph-S-) ligands. We achieve this unprecedentedly large optical response (plasmoelectric effect) in TNPs through the selective manipulation of electronic processes at the Au-thiolate interface. Interestingly, thiophenolates with electron withdrawing (donating) groups (X) produce lambda(LSPR) blue (red) shifts with broadening (narrowing) of localized surface plasmon resonance peak (lambda(LSPR)) line widths. Surprisingly, these experimental results are opposite to a straightforward application of the Drude model. Utilizing density functional theory calculations, we develop here a frontier molecular orbital approach of Au-thiophenolate interactions in the solid-state to delineate the observed spectral response. Importantly, all the spectroscopic properties are fully reversible by exchanging thiophenolates containing electron withdrawing groups with thiophenolates having electron donating groups, and vice versa. On the basis of the experimental data and calculations, we propose that the delocalization of electrons wave function controls the free carrier concentration of Au and thus the LSPR properties rather than simple electronic properties (inductive and/or resonance effects) of thiophenolates. This is further supported by the experimentally determined work functions, which are tunable over 1.9 eV in the X-Ph-S-passivated Au TNPs. We believe that our unexpected finding has great potential to guide in developing unique noble metal nanostructure-organic ligand hybrid nanoconjugates, which could allow us to bypass the complications associated with off-resonance LSPR activation of noble metal-doped semiconductor nanocrystals for various surface plasmon-driven applications.
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