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Metal nanoparticle-catalyzed reactions such as hydrogenation, cross-coupling, carbonylation, and hydroformylation reactions are the most widely used reactions in the pharmaceutical and fine chemical industries. However, there is no operando spectroscopic technique that exists to monitor the size of functioning nanocatalyst. By exploiting localized surface plasmon resonance of catalytically relevant nanostructures, such as monometallic (e.g., Pd, Pt, Ni, Rh, Au, and Cu) nanoparticles and bimetallic core–shell (e.g., Ag-Pd) nanoparticles, we show UV–Vis spectroscopy can be used to determine the size of functioning nanocatalyst. Based on our finite-difference time-domain simulations, it is possible to detect leaching of even a monolayer of atoms from the surface of widely used metal nanocatalysts with a conventional UV–Vis spectrometer. This sensitive, inexpensive and robust spectroscopic approach can be potentially used as in-line process analytical technology (PAT) in pharmaceutical development and manufacturing.

Over the years plasmonic materials have received wide attention for their ability to convert solar into chemical energy. Plasmonic nanoparticles (NPs) exhibit strong electromagnetic-field (EMF) enhancement for the incident light because of the Localized Surface Plasmon Resonance (LSPR). This property has been shown to enhance the photocatalytic performance of nearby semiconductors in the composite, and hybrid photocatalysts build on plasmonic metal nanoparticle and semiconductor. In this presentation, we will focus on copper based hybrid plasmonic nanostructures and optically resonant high dielectric nanostructures for efficient conversion of solar into chemical energy. Our FDTD simulation results predict that the EMF enhancement observed over high dielectric NPs are 2-3 orders of magnitude higher than the plasmonic NPs. This new family of non-plasmonic metal oxide nanostructures is dielectric in nature with high refractive index (> 2). Our simulation results predict that the Mie resonance over these high-dielectric nanostructures can be tuned anywhere from UV-Vis to the near-IR region by controlling the geometry of the nanostructures. We will also show experimental results that validate the simulation results. We utilized size and shape-controlled synthesis techniques to design optically resonant nanostructures with tunable Mie resonance. The optoelectronic properties of these nanostructures are confirmed using a number of spectroscopic techniques. Also, we will show the visible-light enhanced photocatalytic performance of the high dielectric nanostructures for carbon-carbon (C-C) coupling reactions. The design rules developed for the optically resonant nanostructures in our study will potentially have a wide range of applications including the use of these nanostructures for solar-light driven photocatalysis and thin-film solar cell applications.