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Sputter Deposition of Iron Oxide and Tin Oxide Based Films and the Fabrication of Metal Alloy Based Electrodes for Solar Hydrogen Production
| Title: | Sputter Deposition of Iron Oxide and Tin Oxide Based Films and the Fabrication of Metal Alloy Based Electrodes for Solar Hydrogen Production |
| Author: | Sporar, Daniel |
| Description: | This M.S. Thesis describes the fabrication and characterization of n-type iron (III) oxide thin film semiconductors as well as n-type fluorine doped tin dioxide thin film semiconductors for use as the top oxide layer of hybrid multijunction PEC electrodes and as a transparent conductive corrosion resistant layer, respectively. Also described is the fabrication and characterization of various anode and cathode materials in an attempt to devise high quality, cost-effective electrocatalysts for the electrolytic evolution of hydrogen and oxygen gases. Iron (III) oxide thin films were radio frequency sputter-deposited under variable conditions. Dopants were incorporated via co-sputtering in an attempt to enhance photocurrent response and overall film stability in basic media, 33 % potassium hydroxide. Iron (III) oxide thin films deposited with a chamber atmosphere containing 2 % oxygen in argon at 100 W at 400 °C for 110 min demonstrated the highest observed photocurrents of 0.34 mA/cm2 under 0.75 sun illumination; efficiency was 0.56 % at a potential of 0.38 V. The films were also stable. Fluorine doped tin dioxide thin films were fabricated in the same fashion as the iron (III) oxide thin films; samples deposited at 50 W with the chamber atmosphere containing 5 % oxygen in argon at 250 °C for 135 min demonstrated photocurrents of 0.2 mA/cm2, although they lacked stability. Iron (III) oxide was deposited onto the top of a triple-junction amorphous silicon solar cell to investigate its usefulness as a protective oxide layer. Anodes and cathodes that were investigated for enhanced electrocatalytic properties consisted of various materials produced by various methods. Current densities and hydrogen evolution rates were measured. Electrodes demonstrating the greatest performance were made by mixing nickel, aluminum, and molybdenum powders in nickel trays at a ratio of 88:5:7, and then sintering them for four hours in a furnace at 900 °C. The electrodes were then soaked in 33 % potassium hydroxide in order to leach out the aluminum, thus creating porous structures of high surface area. Current densities near 40 mA/cm2 measured at 1.8 V have been demonstrated after 1000 hours of accelerated continuous long-term testing at a potential of 2.2 V. |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1183481021
http://hdl.handle.net/2374.OX/19320 |
| Date: | 2007 |
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