Date of Award
Spring 5-10-2019
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
First Advisor
Dr. Ram Gupta
Keywords
Perovskite, Water splitting, Supercapacitor, OER, HER, pseudocapacitance
Abstract
Recent changes in global weather patterns have accented the need a shift from fossil fuels to a cleaner energy option. As part of an overall plan, hydrogen production for fuel cells offer substantial power without carbon emissions. Overall water splitting, with the aid of a low cost electrocatalyst could prove to be an abundant green fuel source. Utilizing readily available transition metals, three perovskite nanostructures were studied as a multifunctional material for hydrogen production as well as an energy storage material. LaCoO3 (LCO), LaFeO3 (LFO), and LaMnO3 (LMO) were synthesized and characterized by X-ray diffraction (XRD) and then dip coated onto nickel foam as electrodes in a standard three electrode system. The electrochemical properties were analyzed with electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) for its electro-catalytic activity towards both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) as well as its effectiveness as a supercapacitor. It was shown that electrocatalytic activity toward OER was highly dependent on the material composition. Accordingly, LFOhad the lowest overpotential voltage of 316 mV at 10 mA/cm2 compared with 376 mV (LCO) and 419 mV (LMO). Toward HER, LMOshowed overpotential voltage of 176 mV at 10 mA/cm2, while LCO and LFO showed 221 mV and 230 mV, respectively. Measured over a range of current densities, the specific capacitance of LCO remained higher (~100) F/g over LCO (~45 F/g) and LFO (~35 F/g). An altered synthetic method was employed to investigate the affects of structure directing (chelating) agents on electro-catalytic activity. Replacement of glycine with citric acid in the synthesis process was found to improve the structure characteristics and electrochemical properties of LFO. Structural improvements for LCO and LMO were unfavorable with alteration as shown by XRD. Further investigation and understanding of structure directing agents and oxygen vacancy manipulation is needed for greater material efficiency.
Recommended Citation
Martinez, Xavier, "LANTHANUM-BASED PEROVSKITES AS AN EFFECTIVE ELECTROCATALYST FOR WATER SPLITTING AND ENERGY STORAGE APPLICATIONS" (2019). Electronic Theses & Dissertations. 387.
https://digitalcommons.pittstate.edu/etd/387
