Addressing the Effects of Size‐dependent Absorption, Scattering, and Near‐field Enhancements in Plasmonic Catalysis

Abstract

Studies on surface plasmon resonance (LSPR) mediated catalytic transformations have focused on quantification of reaction rates and investigation on enhancement mechanisms. However, the establishment of structure-performance relationships remains limited. For instance, the importance of nanoparticle size remains overlooked, and relatively large nanoparticles (> 50 nm in size) are generally employed as catalysts. Herein, we unravel how plasmon decay pathways (absorption and scattering efficiencies) and electric field enhancements as a function of size dictate plasmonic catalytic performances. We employed Ag NPs having 12-50 nm in size as a proof-of-concept catalysts, and the LSPR-mediated oxidation of p-aminothiophenol to p,p'-dimercaptoazobenzene as a model reaction. Our data and simulations revealed that the LSPR-mediated activities displayed a volcano-type variation with size, which was dependent on the balance among near field enhancements, absorption, and scattering. As this transformation is driven by the chargetransfer of LSPR-excited hot-electrons to adsorbed O 2 molecules, the variations in the optical absorption as a function of size represented the dominant contribution to the plasmonic catalytic activities. We believe our results shed important insights over the optimization of physical and chemical parameters in plasmonic nanoparticles in order to maximize plasmonic catalytic activities.

Plasmonic catalysis with designer nanoparticles

“…58,59 As absorption is related to the generation of LSPR excited charge carriers, i.e., hot electrons and holes, it is expected that the relative ratio of absorption and scattering is an important parameter that would influence performances in plasmonic catalysis. 60 To precisely study the effect of size in plasmonic catalysis, NPs with controlled sizes in a reasonable range that is interesting for plasmonic catalysis are required.…”

“…To address this challenge, we developed a strategy for the synthesis of Ag NPs in the 50-12 nm range. 60 The approach was based on the use of Ag NPs 50 nm in size as starting materials to a controlled etching process in the presence of HNO 3 (Figure 3A). By controlling the HNO 3 concentration and keeping the etching time constant at 40 min, the extent of chemical etching, that leads to a decrease in size, can be tuned.…”

Visible light plasmon excitation of silver nanoparticles against antibiotic-resistant Pseudomonas aeruginosa

“…The copyright holder for this preprint this version posted January 12, 2020. ; https://doi.org/10.1101/2020.01.10.902676 doi: bioRxiv preprint catalysis (3), SERS (4), electroanalytical sensors (5), plasmonics (6), photonics (7) and others.…”

Efficient Plasmon-Mediated Energy Funneling to the Surface of Au@Pt Core–Shell Nanocrystals

“…11,24,30,48,49 For these reasons, small coreshell NCs can provide particularly efficient photoabsorption and charge/energy delivery to surface catalytic sites. It is also worth noting that the maximum plasmonic electric field strength at the surface of an isolated Au NC depends only weakly on NC size, 41,[50][51][52] while the average field enhancement integrated over the NC surface is larger for smaller NCs. 29 Intense local fields can trigger chemical reactions 53 and provide in situ probes of reaction mechanism via surface enhanced Raman spectroscopy (SERS).…”