First Name:
Katarina
Last Name:
Hauser
Major Department:
Chemistry
Thesis Director:
Michael Hambouger
Date of Thesis:
May 2014
Cobaloximes are promising catalysts for the hydrogen evolution half-reaction and could be used as cathodic catalyst for renewable energy storage system. In an ideal situation, a cobaloxime would be stably attached to an electrode surface via covalent bonds, entrapment, or hydrophobic interactions and be catalytically active at neutral pH in aqueous conditions. At present, only a handful of studies have been conducted in water, and these indicate that catalytic turnover generally is restricted to acidic conditions. In the present work, efforts have been made to increase the stability of cobaloxime adsorbed to an electrode surface, while increasing the accessible pH range of the cobaloxime catalyst by shifting the cobalt-based redox processes to more negative potentials. A novel cobaloxime, Co(dNhgBF2)2, was synthesized in a similar manner to two known cobaloximes, Co(dpgBF2)2 and Co(dmgBF2)2. The three cobaloximes have been characterized by CHN analysis, magnetic susceptibility, 1H NMR and 13C NMR spectroscopy (when applicable), UV-visible spectroscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry. The two known cobaloximes, Co(dmgBF2)2 and Co(dpgBF2)2, provided results comparable to published material. The novel cobaloxime, Co(dNhgBF2)2, showed increased electron density on the cobalt ion and behavior that otherwise mirrored the known cobaloximes. Titrations with trifluoroacetic acid and p-toluenesulfonic acid demonstrated all three cobaloximes were catalytically active for hydrogen production. Efforts were made to adsorb these catalysts to a modified electrode surface, in order to monitor their behavior in water across a range of pH. The results of these efforts will be discussed, although improved performance in water has not yet been demonstrated.