Photoelectron Spectroscopic Studies of Energy Converting Semiconductor Materials and Their Interfaces with Molecular Gases

Advancement in science and technology has brought rapid development in manufacturing, transportation, communication, health, and entertainment. These developments have increased the global energy demand. This increasing energy demand has forced policy makers and the scientific community to search for alternative energy sources and optimize the conventional sources of energy. For a long time, people have been trying to find more efficient ways to convert other forms of energies such as solar, wind, and geothermal energy to electrical energy. To improve the efficiency of energy conversion, new materials have been studied constantly. In the last few decades, III-V semiconductors, halide perovskites, and metal oxides are being studied as promising energy converting materials in devices like solar and fuel cells. However, lack of molecular-level understanding of these semiconductor surfaces and their interfacial interactions with different gases in the ambient working environment has hindered the practical application of those materials on a commercial scale. One of the promising materials currently being studied is solar absorbing materials like Ag-Bi-I based nanoparticles and GaAs and CO oxidizing catalysts like CeO₂. The research on this dissertation is focused on the molecular level study of surface states and interfacial interactions with molecular gases of GaAs, Ag-Bi-I based nanoparticles, and CeO₂ as promising and potential replacement for Pt and other expensive novel metals in solar and fuel cells.