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Zhou, Hao

University of British Columbia

Oxygen evolution reaction (OER) is a chemical process to generate molecular dioxygen from water. The process involves the liberation of four protons and electrons, and normally requires a high overpotential to break O-H bonds and form O-O bonds. The development of efficient OER strategies in water oxidation (WO) and the understanding of such catalytic systems have therefore been a major focus in the drive for a cleaner energy alternative. In this thesis, we proposed and evaluated a plausible catalytic mechanism mediated by a benchmark molecular iridium catalyst with the help of density functional theory (DFT) calculation. From such studies, we noticed the direct participation of ligand in the oxo-oxo coupling process, which may lower the activation energy for this rate determining step of the OER. Inspired by the computational studies, we designed and synthesized a series of novel half-sandwich Cp*Irᴵᴵᴵ complexes (Cp* = C₅Me₅-) based on amino acid ligands. These catalysts showed impressive turnover number (TON) and turnover frequency (TOF) when using sodium periodate as the sacrificial oxidants (SOs). While using tetravalent cerium salts as the primary tool to evaluate the catalytical performance of such catalysts, we observed that rapid hydrolysis of tetravalent cerium formed cerium oxide nanoparticles (NPs), even in a strongly acidic environment (e.g., 0.1 M HNO₃ solution). The solution structures of such systems have been successfully characterized by modern small-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) techniques. These results provide valuable insights for computational-aid catalyst design and highlight the importance of SOs when examining the catalytical performance of OER.

Text

2024-10-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82969

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/