Nanoplasmonic Sensing of Materials for Energy Applications

Abstract: Sensors are omnipresent in our daily life. They are used in many applications ranging from the touch screen in our smartphones to more critical contexts such as pollution monitoring. Although sensors have been developed for a long time, the demands are continuously increasing and many sensors still suffer from insufficient selectivity and/or sensitivity. The development of nanosensors has been suggested as one solution to push sensor performance boundaries further by exploiting the unique phenomena occurring at the nanoscale. One of the nanotechnology subareas of particular interest for sensing applications is nanoplasmonics, which explores the localized surface plasmon resonance (LSPR) phenomenon occurring in metal nanoparticles. In this thesis, nanoplasmonic sensing is developed and utilized in the context of the current challenges in the energy and environmental fields, or more specifically, the hydrogen economy, Carbon Capture and Storage (CCS) and solar energy harvesting technologies. In the first part, direct nanoplasmonic sensing based on AuPd alloy nanoparticles is explored for use as next-generation hydrogen sensors. To facilitate the nanofabrication of such alloy nanostructures, a bottom-up nanofabrication strategy for producing supported alloy nanoparticles with excellent control of their composition is developed. The performance of the fabricated AuPd alloy hydrogen sensors is then assessed and favorably compared to the performance targets set for hydrogen sensors to be used in fuel cell vehicles. In the second part, indirect nanoplasmonic sensing is established as an analytical tool to assess key properties of energy related materials for CCS and organic photovoltaics. The first study constitutes an investigation of CO2 adsorption in a microporous polymer, and the optical determination of the CO2 isosteric heat of adsorption. The second study addresses the thickness dependence of the glass transition temperature of a polymer:fullerene blend used as light absorber layer in organic photovoltaic devices. These two studies establish indirect nanoplasmonic sensing as a reliable and important analytical tool for the quantitative assessment of material properties of systems highly relevant for energy applications.