TIME to SHINE: Plasmon-Enhanced Raman Spectroscopy for Catalysis

Abstract

This PhD thesis focusses on the development of Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) in the field of heterogeneous catalysis. SHINERS is a relatively new technique and has the potential to be a very useful tool for understanding catalytic processes on the nanoscale. This is achieved by using gold nanoparticles as nanoantennae and bringing them in close proximity of the catalyst, on the scale of 1-10 nanometers. When the gold nanoparticles are illuminated with laser light of the resonance frequency, they can report on catalytic reactions taking place on the surface of the catalyst. This can provide in depth understanding of how catalysts operate, and can aid in the development of more efficient and sustainable catalytic processes. In this thesis, we extend the applicability of SHINERS in the field of heterogeneous catalysis in several ways. In Chapter 1, we introduce Plasmon-Enhanced Raman Spectroscopy (PERS) and specifically its subcategory SHINERS and Tip-Ehanced Raman Spectroscopy, TERS, in the field of catalysis. In Chapter 2 we demonstrate the preparation of Shell-Isolated Nanoparticles and Tips and we extend the applicability of TERS to aqueous environments. In Chapter 3 we prepare new plasmonically active superstructures suitable for SHINERS studies of catalytic reactions in aqueous ennvironments. We do this by depositing the gold nanoparticles on large silica colloids and then coating this entire structure with a thin silica shell. In Chapter 4 we show that we can study sequential reactions of complex organic molecules and their reverse of the type A -> B -> C -> B -> A over a noble metal catalyst, in particular the hydrogenation of phenylacetylene into ethylbenzene and the tevese dehydrogenation. In Chapter 5 we introduce a new method of preparation that enables SHINERS investigation of non-noble metal catalysts, which are industrially relevant. We use Ni as an example and study acetylene hydrogenation. Finally, Chapter 6 provides both a summary and outlook with unpublished results which may form a foundation for future work.