Resonances of nanoparticles with poor plasmonic metal tips

Abstract

The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

Bimetallic nanostructures: combining plasmonic and catalytic metals for photocatalysis

“…Since many metal combinations do not, some plasmonic-catalytic bimetallic geometries result in a gradient-alloy structure, which can also be beneficial for enhancing the plasmonic fields. For example, electron energy loss spectroscopy maps of Au octopods with AuPd tips show spatially localized resonances around the tips [97]. Alternatively, one can sacrifice distinct faceting by conventional alloying techniques like thermal annealing [92,98], or new colloidal synthesis techniques like probe-based lithography [99].…”

Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

“…The era of the application of EELS for plasmonics has changed since 2007, when Nelayah et al [140] and Bosman et al [141] reported, almost simultaneously, first examples of spatial mapping the SPRs of individual nanoparticles at the nanometer scale by mono-chromated EELS in a STEM using the spectrum imaging (SI) technique developed by Jeanguillaume and Colliex in 1989 [142]. Ever since the above-mentioned precedent studies, EELS has been used to map plasmon resonances of different solid nanostructures including spherical nanoparticles, nanorods/nanowires, nanocubes, nanodisks, nanoprisms, nanostars, nanosquares, and nanodecahedra [31,50,[143][144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162]. Along with its capability to give information with high spatial and energy resolutions, EELS has the ability to reveal full modal spectrum including dark plasmon modes, which are invisible to optical spectroscopy techniques, in coupled nanostructures [31,145,148,152,155,163,164].…”

Bifunctional Platinum Tetrapods: High‐Performance Catalyst for Hydrogenation of Aromatic Nitro Compounds and Electrochemical Sensor for Hydrazine.

“…Octopods of Au and Pd combine the catalytic and plasmonic of each element in a single nanostructure, prompted us to develop a facile one‐step and high‐yield synthesis for platinum tetrapods (Pt TPs) which may have enhanced catalytic properties than Pt NPs . Hollow carbon nanospheres (HCNSs), template from iron oxide nanoparticles using glucose as carbon source, are utilized to encapsulate the high‐performance Pt TPs to formulate the confined catalytic nanoreactors for hydrogenation of various nitro aromatic compounds and for electrochemical oxidation of hydrazine (Scheme ).…”