Alloy Plasmonics - Fundamentals and Applications
Doktorsavhandling, 2022

Alloys have for a long time been important in the development of our society; from the Bronze Age, where man learned how to alloy copper with tin, to today, where many products are made of steel and aluminum alloys. Similarly, but maybe not as generally well known, alloys have lately been proposed as a new paradigm in nanophotonics, to tailor optical properties of nanomaterials that find applications within telecommunication, sensing, or biotechnology. Furthermore, alloys are explored in heterogeneous catalysis to develop solutions to increase activity and selectivity of chemical processes. Nanophotonics and catalysis, separately and in combination, are the focus of this thesis. Specifically, we have compiled a library of alloy complex dielectric functions for the late transition metals by utilizing time-dependent density-functional theory. The calculated dielectric functions were benchmarked by (i) nanofabricating series of alloy nanoparticle arrays with systematically varying composition, (ii) measuring their plasmonic properties, and (iii) comparing these properties with electrodynamic simulations of alloy nanoparticles, using the dielectric function library as the input. These dielectric functions allowed us further to screen the absorption efficiency of nanoparticles of multiple combination of size and composition to show the superior performance of alloys compared to their neat constituents.

The second theme in this thesis is plasmon-enhanced catalysis. In this field, there is a continuous discussion regarding the reaction enhancing mechanisms when noble metal catalyst nanoparticles are irradiated with visible light during a catalytic reaction. Here we investigated the role of photothermal enhancement of reactions by tailoring the catalytic activity of nanofabricated particles without radiation by means of alloying Pd with Au, while keeping the optical absorption cross section constant, as confirmed by electrodynamics simulations using our dielectric function library as the input.
Temperature is a crucial parameter during catalysis in general and photocatalysis in specifically. However, it is intrinsically difficult to measure the temperature of nanoparticles with traditional methods. Therefore, we presented a hydrogen nanothermometry method that allows measuring nanoparticle temperature directly and noninvasively via the temperature dependent phase transition during Pd-hydride formation. We showed that the Pd particle temperature during light-induced heating can be measured with a resolution of 1 °C.

sensing

gold-palladium

nanothermometry

palladium-hydride

nanoalloys

photothermal

plasmonics

CO oxidation

heterogeneous catalysis

dielectric function

PJ
Opponent: Prof. Guillaume Baffou, Institut Fresnel, CNRS, Aix Marseille University, Marseille

Författare

Christopher Tiburski

Chalmers, Fysik, Kemisk fysik

A Library of Late Transition Metal Alloy Dielectric Functions for Nanophotonic Applications

Advanced Functional Materials,;Vol. 30(2020)

Artikel i vetenskaplig tidskrift

Light-Off in Plasmon-Mediated Photocatalysis

ACS Nano,;Vol. 15(2021)p. 11535-11542

Artikel i vetenskaplig tidskrift

Optical Hydrogen Nanothermometry of Plasmonic Nanoparticles under Illumination

ACS Nano,;Vol. In Press(2022)

Artikel i vetenskaplig tidskrift

Engineering Optical Absorption in Late Transition-Metal Nanoparticles by Alloying

ACS Photonics,;Vol. 10(2023)p. 253-264

Artikel i vetenskaplig tidskrift

Alloys have been used by mankind even before understanding what they actually were and the most prominent example from history is probably the Bronze Age, where man started to alloy copper with tin, which provided tools with increased hardness, stiffness, or ductility.  Alloys are the combination of two or more metals, intermixed at the atomic level, that are produced with the goal to improve mechanical, electrical, thermal, or chemical properties. Focusing on the present, we find alloys in almost every macroscopic metal object.

At the same time, the concept of alloying is still in its infancy in younger areas of science and technology, like in the field of nanoplasmonics that is focused on investigating the interaction of light with nanoparticles. The word nanoparticle gives the small but distinct hint that we are in the world of nanometer sized objects. One nanometer compares to a meter like a euro coin to the size of our planet. In plasmonic applications the use of alloys is to-date still limited to a small number of systems. This is mainly due to a lack of understanding of the fundamental optical properties of alloys in general, and a lack of complex dielectric functions of alloys in particular. The latter is critical since dielectric functions are a key resource for being able to predict the response of nanostructures to light by means of modeling or electrodynamic simulations. Such predictions, in turn, are important to both rationally design and fine-tune alloy nanostructures for their intended applications.

In this thesis, I have contributed to the discovery of such dielectric functions for ten different alloy systems, and then applied them together with a range of nanofabricated alloy nanoparticle systems in combined experimental and theoretical studies of alloy nanoparticles in the world of plasmonics and catalysis.

Wallenberg Academy Fellow 2016

Knut och Alice Wallenbergs Stiftelse (KAW2016.0210), 2017-07-01 -- 2022-06-30.

Styrkeområden

Nanovetenskap och nanoteknik

Ämneskategorier

Fysikalisk kemi

Fysik

Nanoteknik

Metallurgi och metalliska material

Den kondenserade materiens fysik

Infrastruktur

Chalmers materialanalyslaboratorium

Nanotekniklaboratoriet

ISBN

978-91-7905-720-6

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5186

Utgivare

Chalmers

PJ

Opponent: Prof. Guillaume Baffou, Institut Fresnel, CNRS, Aix Marseille University, Marseille

Mer information

Senast uppdaterat

2023-11-08