AbstractsChemistry

Polyoxometalates (POMs) have been attracting interest from researchers in the fields of Inorganic Chemistry, Physical Chemistry, Biomolecular Chemistry, etc. Their unique structures and properties render them versatile and facilitate applications in medicine, magnetism, electrochemistry, photochemistry and catalysis. In particular, toxic compound (chemical warfare agents (CWAs) and toxic industrial compounds (TICs)) decontamination and solar energy conversion by POM-based materials have becoming promising and important research areas that deserve much attention. The focus of this thesis is to explore the structural features of POMs, to develop POM-based materials and to investigate their applications in toxic compound decontamination and solar energy conversion. The first part of this thesis gives a general introduction on the history, structures, properties and applications of POMs. The second part reports the synthesis, structures, and reactivity of different types of POMs in the destruction of TICs and CWAs. Three tetra-n-butylammonium (TBA) salts of polyvanadotungstates, [n-Bu4N]6[PW9V3O40] (PW9V3), [n-Bu4N]5H2PW8V4O40 (PW8V4), [n-Bu4N]4H5PW6V6O40.20H2O (PW6V6) are discussed in detail. These vanadium-substituted Keggin type POMs show effective activity for the aerobic oxidation of formaldehyde (a major TIC and human-environment carcingen) to formic acid under ambient conditions. Moreover, two types of POMs have also been developed for the removal of CWAs and/or their simulants. Specifically, a layered manganese(IV)-containing heteropolyvanadate with a 1:14 Stoichiometry, K4Li2[MnV14O40].21H2O has been prepared. Its catalytic activity for oxidative removal of 2-chloroethyl ethyl sulfide (a mustard simulant) is discussed. The second type of POM developed for decontamination of CWAs and their simulants is the new one-dimensional polymeric polyniobate (P-PONb), K12[Ti2O2][GeNb12O40].19H2O (KGeNb). The complex has been applied to the decontamination of a wide range of CWAs and their simulants under mild conditions and in the dark. The third part of this dissertation addresses the use of POM-based materials in photocatalytic hydrogen evolution reactions. The structures, characterizations and catalytic hydrogen generation activities of a new tri-nickel-containing Wells-Dawson POM, [Ni3(OH)3(H2O)3P2W16O59]9- and a new hybrid material that combines POMs, Pt nanoparticles (NPs) and MOFs are investigated. Table of Contents  – Chapter 1 Introduction: Overview of the Structures, Properties and Applications of Polyoxometalates in Toxic Compound Decontamination and Solar Energy Conversion. 1  – 1.1 General Structures of POMs. 2  – 1.2 Catalytic Properties of POMs in Toxic Compound Decontamination. 7  – 1.2.1 Air-based oxidation of organic compounds by POMs. 7  – 1.2.2 The use of POMs in the decontamination of toxic compounds. 9  – 1.3 The use of POMs in solar energy conversion. 12  – 1.4 Goal of this work and outline. 14  – References. 16  – Chapter 2 Polyvanadotungstates for Aerobic… Advisors/Committee Members: Lian, Tim (Committee Member), Scarborough, Christopher C (Committee Member), Hill, Craig L (Thesis Advisor).