Abstract
Multi-metallic alloy nanoparticles (NPs) can offer a promising route for the integration of multi-functional elements by the adaptation of advantageous individual NP properties and thus can exhibit the multi-functional dynamic properties arisen from the electronic heterogeneity as well as configurational diversity. The integration of Pt-based metallic alloy NPs are imperative in the catalytic, sensing, and energy applications; however, it usually suffers from the difficulty in the fabrication of morphologically well-structured and elementally well-alloyed NPs, which yields poor plasmonic responses. In this work, the improved morphological and localized surface plasmon resonance (LSPR) properties of fully alloyed bimetallic AgPt and monometallic Pt NPs are demonstrated on sapphire (0001) via the one-step solid-state dewetting (SSD) of the Ag/Pt bilayers. In a sharp contrast to the previous studies of pure Pt NPs, the surface morphology of the resulting AgPt and Pt NPs in this work are significantly improved such that they possess larger size, increased interparticle gaps, and improved uniformity. The intermixing of Ag and Pt atoms, AgPt alloy formation, and concurrent sublimation of Ag atoms plays the major roles in the fabrication of bimetallic AgPt and monometallic Pt NPs along with the enhanced global diffusion and energy minimization of NP system. The fabricated AgPt and Pt NPs show much-enhanced LSPR responses as compared to the pure Pt NPs in the previous studies, and the excitation of dipolar, quadrupolar, multipolar and higher-order resonance modes is realized depending upon the size, configuration, and elemental compositions. The LSPR peaks demonstrate drastic alteration along with the evolution of AgPt and Pt NPs, i.e., the resonance peaks are shifted and enhanced by the variation of size and Ag content.
Highlights
In the last decade, metallic nanoparticles (NPs) have received a great deal of research attentions due to their various applicability in electronics, photonics, energy, catalysis, sensors, storages, and biomedicines [1,2,3,4,5,6,7]
The systematic annealing of the Ag7nm/Pt1.5nm bilayer series demonstrated well-developed AgPt and Pt nanostructures based on the solid-state dewetting (SSD) and the gradual evolution of size, spacing, areal density, and elemental variation of isolated semi-spherical NPs were observed at various temperatures
In summary, the AgPt and Pt NPs with various sizes and configurations have been demonstrated on sapphire (0001) based on the solid-state dewetting of the three series of Ag/Pt bilayers
Summary
Metallic nanoparticles (NPs) have received a great deal of research attentions due to their various applicability in electronics, photonics, energy, catalysis, sensors, storages, and biomedicines [1,2,3,4,5,6,7]. The capability of metallic NPs to interact with the photons of various wavelengths induces the localized surface plasmon resonance (LSPR), which has tremendously scaled up the range of functionality and applicability of NPs [12,13,14]. The LSPR is a collective oscillation of electrons on the plasmonic NP surface in resonance with the incident photons, which results in the strong absorption or scattering of light as well as intensification of the electromagnetic fields around the NPs. As the LSPR effect of metallic NPs is closely related to the size, shape, composition, and metal-support interactions, it can be readily exploited to enhance/alter the electrical, magnetic, optical and catalytic properties for the corresponding devices [15]. Achieving LSPR from the metallic NPs in the broadband wavelength is still challenging as well as demanding in various applications such as perfect absorbers in solar cell applications [18, 19]
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