UC San Diego

Polyoxometalates (POMs) are anionic metal oxo clusters composed of groups 5 and 6 transition metals such as vanadium, niobium, tantalum, molybdenum, and tungsten. These metals, in high oxidation states, are coordinated to terminal oxo ligands and connected through bridging oxo ligands, making POMs oxidation-inert but easily reducible. The reduction processes in POMs are reversible, which coupled with their structural integrity, makes them ideal for developing novel materials for applications in energy storage and conversion, molecular electronics, and catalysis. This dissertation specifically discusses POM applications in the electrosynthesis of metal oxide frameworks and thermogalvanic cell electrolytes.Chapter 3 presents the development of new coordination networks using Preyssler anions as modular building blocks using electrocrystallization, a method that uses electrochemical redox reactions to form crystalline compounds. The resulting structures exhibit one-dimensional chains connected through cap-to-cap coordination. Notably, these are the first examples of electrocrystallized Preyssler-based metal oxide coordination networks. The chapter details the synthetic processes, structural analysis, and characterization of these coordination networks. Chapter 4 discusses the utilization of POMs as potential electrolytes in thermogalvanic cells, which are promising for converting low-grade thermal energy into electrical energy. The chapter presents two POM thermogalvanic systems based on Dawson and Preyssler-type clusters. The chapter covers the electrochemical analyses of the systems and discusses potential factors, such as ion concentration and pH, that could impact the ?e values.