Quantum dots (QDs) are promising photocatalysts due to their large extinction coefficient, large surface area-to-volume ratio, and stability upon irradiation. QDs have been studied in photocatalytic hydrogen production, CO2 reduction, and reduction of small organic molecules such as nitrobenzene. This dissertation describes the application of QDs in two photocatalytic cross-coupling systems and the investigation into two strategies to modify the surface of QDs to improve the reactivity and/or the selectivity of photocatalytic cross-coupling reactions, namely (i) increasing the disorder of the surface, and (ii) introducing coordinating ligands to transiently bond to intermediates of transition metal catalysts. In bulk solution, the ligands of QDs prevent the dots from aggregating and precipitating. For the QDs to act as photocatalysts, the substrates must approach the core of QDs either by diffusing through the ligand shell of QDs or forming chemical bonds with the core. The two projects detailed in chapters 2 and 3 demonstrate that the surface of QDs can be tuned to (i) enhance the rate of a photo-redox C-C coupling reaction by accelerating the rate-limiting hole-transfer step, through the preparation of a more permeable surface for reactants, and (ii) improve the selectivity and reactivity of a Pd-photocatalytic Heck reaction by using iso-nicotinic acid as the ligand to accelerate the energy transfer from QDs to a photogenerated Pd-intermediate through coordination. The projects described in this dissertation provide the basis for the design of QDs surfaces so that unique reactivity and selectivity can be discovered.

Creator

• Zhang, Zhengyi

DOI

• https://doi.org/10.21985/n2-fytc-me56

Subject

• Chemistry

Language

• en

Alternate Identifier

• http://dissertations.umi.com/northwestern:15493
• etdadmin_upload_798062

Date created

• 2021-01-01

Resource type

• Dissertation

Rights statement

• In Copyright