AN INVESTIGATION OF THE CHEMISTRY, THERMODYNAMICS AND CATALYTIC ACTIVITY OF MOLYBDENUM CARBIDES

These studies investigate the chemistry and stability of molybdenum carbides as an electrocatalyst. Due to their unique electronic properties, molybdenum carbides are purposed as electrocatalysts for reaction systems such as hydrogen evolution reaction, bifunctional water splitting and CO oxidation. In this study, various synthesis processes were utilized to produce different types of molybdenum carbide with varying properties of particle size, surface area and excess carbon. The samples characterized by XRD accompanied by Whole Profile Fitting, Electron Microscopy, Gas Adsorption (surface area) and XPS. These synthesis processes were refined using fundamental thermodynamic analyses. These analyses highlight regions of stability of different phases of the carbide under differing conditions of temperature, partial pressures and hydrocarbons. The phase stabilities of the molybdenum carbides in aqueous electrolytes were investigated as well in this study. Using thermodynamic modeling, the dependence of oxide formation potentials on pH at different temperatures is established. This was then used to guide the CV studies of the different molybdenum carbide samples. It was observed that the surface chemistry of the carbide species influences the electrochemical activity for hydrogen evolution reaction. The results in this dissertation provide a comprehensive guide for the refinement of synthesis procedures as well as a roadmap for development of molybdenum carbide as an electrocatalyst