Graduate Program

Chemistry

Degree Name

Master of Science (MS)

Semester of Degree Completion

2012

Thesis Director

Svetlana Mitrovski

Thesis Committee Member

Douglas G. Klarup

Thesis Committee Member

Barbara Lawrence

Thesis Committee Member

Radu F. Semeniuc

Abstract

The implementation of fuel cells into commercial usage is prenominally dependent on the activity of cathode at which oxygen reduction reaction (ORR) takes place. Fuel cells currently use noble metals like platinum, palladium etc as cathode for the reduction reaction. These metals showed poor performance during changes in red ox environment. Perovskite oxides which were proven to be efficient as cathodes in solid oxide fuel cells operating at high temperature was studied to understand its ability to carry out ORR in alkaline fuel cells operating at room temperature.

La1-XSrxMnO3 (LSMO), thin film perovskite oxide, a single crystal film was grown epitaxially on SrTiO3 substrate by pulsed laser deposition technique (PLD). Surface characterization of LSMO thin film by atomic force microscopy (AFM) confirmed the LSMO thin-film to be very smooth and compact. The surface characterized LSMO when characterized by cyclic voltammetry in 1M NaOH for its ability to oxygen reduction reaction (ORR) showed two different active states. LSMO without any pretreatment in anodic region was found to be active towards ORR. LSMO when tested for ORR after anodic polarization and pretreatment showed no ORR activity. LSMO thin-film electrode when modified by spontaneous deposition of low concentrations of silver nitrate solutions showed higher ORR activity compared to the LSMO thin film electrode modified with higher concentrations of silver nitrate solution. Also XPS analysis of Ag modified LSMO thin film electrode prior to any electrochemical characterization confirmed the deposition of silver atoms onto the LSMO thin-film.

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