Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UC Davis Electronic Theses and Dissertations (2024)

Water splitting is a promising but challenging solution to alleviate the urgent fuel crisis. While the hydrogen-evolution reaction provides the powerful hydrogen gas as a renewable energy source, the high energy barrier of the anodic oxygen-evolution reaction (OER) limits the overall water splitting efficiency. While heavy metal oxides have been found to be the highly efficient OER catalysts, nature employs the oxygen-evolving complex (OEC) in the photosystem II, which consists of a Mn4O5Ca cluster. It generates most of the O2 in the world in a highly efficient and persistent manner. Inspired by the OEC cluster, in this dissertation, we synthesized biogenic manganese oxides (BioMnOx) using a multicopper oxidase Mnx for OER catalysts. Chapter 1 will provide background information about the OER catalysts, the Mnx protein and Electron Paramagnetic Resonance (EPR) spectroscopy. Chapter 2 will explore the potential of the BioMnOx as OER catalysts and the structure- function relationship. Chapter 3 will investigate Co-doping effect of BioMnOx as well as the structural elucidation of Co-doped BioMnOx using X-ray Absorption Spectroscopy (XAS). On the mechanistic side of the story, Chapter 4 investigates the first row transition-metal ion-inhibition effect of Mnx. EPR spectroscopy has been proven to be a powerful tool to selectively probe the active sites and the metal binding sites of Mnx. Understanding the mechanism of the inhibition effect provides fundamental knowledge about the Mnx mecha- nism and provide information for formulating and optimizing BioMnOx synthesis. Chapter 5 extends the usage of EPR spectroscopy to other metalloprotein and inorganic systems.

    Cover page: Exploring the potential of biogenic manganese oxides as water oxidation catalyst and investigating Mn oxidation mechanism using Electron Paramagnetic Resonance (EPR) spectroscopy
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2022)
    S/N crosstalk species derived from the interconnected reactivity of H2 S and NO facilitate the transport of reactive sulfur and nitrogen species in signaling, transport, and regulatory processes. We report here that simple Fe2+ ions, such as those that are bioavailable in the labile iron pool (LIP), react with thionitrite (SNO- ) and perthionitrite (SSNO- ) to yield the dinitrosyl iron complex [Fe(NO)2 (S5 )]- . In the reaction of FeCl2 with SNO- we were able to isolate the unstable intermediate hydrosulfido mononitrosyl iron complex [FeCl2 (NO)(SH)]- , which was characterized by X-ray crystallography. We also show that [Fe(NO)2 (S5 )]- is a simple synthon for nitrosylated Fe-S clusters via its reduction with PPh3 to yield Roussin's Red Salt ([Fe2 S2 (NO)4 ]2- ), which highlights the role of S/N crosstalk species in the assembly of fundamental Fe-S motifs.
      Cover page: Thionitrite (SNO−) and Perthionitrite (SSNO−) are Simple Synthons for Nitrosylated Iron Sulfur Clusters
      Top