Nanoparticle Synthesis within Nanoreactor Templates and Their Applications


Nanotechnology research broadly encompasses the exploration of the unique chemical,optical, electronic, or biological properties of materials with dimensions < 1 µm. Inorganic nanoparticles are one such class of materials, with properties that are exceptionally sensitive to particle size and structure. This is especially evident in the field of heterogeneous chemical catalysis, where the surface of the material dictates the reaction outcome. However, synthesizing nanoparticles of a desired size, composition, or shape on demand is a persistent challenge, as conventional synthesis approaches often require extensive trial and error to synthesize the preferred particle product, assuming it is possible at all. This thesis introduces two nanoreactorbased strategies, that aim to push the limits of high-yield and modular particle synthesis compatible with chemical catalysis. It further aims to address challenges with measuring the reactivity of low areal-density polyelemental particles synthesized within nanoreactors, and in so doing, provide avenues towards high throughput screening of complex nanoparticle libraries. Chapter One provides a comprehensive introduction to the state-of-the-art with regards to nanoparticle synthesis, and introduces the challenges associated therein. It further introduces the nanoreactor as a robust synthetic alternative, especially for applications in particle synthesis for rapid chemical catalyst discovery. Chapter Two describes a method to synthesize nanoparticles by isolating small volumes of particle precursors within a nanohole reactor, followed by reductive annealing to yield site-isolated nanoparticles. The process described is materials-general and provides a significant degree of size4 control while maintaining monodispersity of the product population. Finally, it provides fundamental insight into the role of reactor geometry on the preferred final position of the particle products. Chapter Three reports a solution-based nanoreactor synthesis scheme, which dramatically increases the throughput of particle synthesis. In this strategy, hollow silica shells are used to isolate and synthesize nanoparticles, and we discover via ex situ, in situ, and bulk-characterization strategies that polymer incorporation is key to a dramatic improvement in the yield of individual particles within each shell. Chapter Four discusses strategies to address the challenge of probing gas-phase reactivity of a low particle-density planar catalyst. The challenge is separated into two steps, with this chapter focused on reactor cell design and testing. The chapter concludes with the proposal of a capillary tube-based strategy for locally screening a library of nanomaterials on a planar surface. Chapter Five describes gas-phase cryogenic distillation of product molecules as a worthwhile strategy to measure the reactivity of a small particle population. This strategy is used to selectively adsorb a hydrocarbon (1-butene) on an adsorbent powder, which can be detected by infrared spectroscopy. Finally, Chapter Six provides an outlook on the field of nanoreactor templated nanoparticle synthesis and highlights several worthwhile future research directions.

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