MSE MS Thesis Defense of Peter Giouard

1:30 pm on Tuesday, August 28, 2012
3:30 pm on Tuesday, August 28, 2012
15 Saint Mary's Street, Rm 105
TITLE: Development of core-shell nanostructured corrosion-resistant photoanodes for hydrogen generation ABSTRACT: Efficient and economical photoanodes used in photoelectrochemical cells (PEC) to produce hydrogen gas by water decomposition using sunlight must both absorb a large portion of incident solar radiation and be stable in alkaline or acidic electrolytic solutions. While smaller bandgaps are necessary to efficiently absorb visible light, only large bandgap materials that absorb primarily UV radiation are known to be stable in photoelectrochemical cells. A promising method of increasing the absorption of photoanodes while retaining corrosion resistance is to create heterostructured materials that feature a low-bandgap material encapsulated by a corrosion-resistant metal oxide layer. In this work, two methods of fabricating heterostructured photoanodes through electrospray deposition of particles and post-deposition sintering were investigated. In the first method, layered photoanodes were fabricated using a needle-to-plane electrode geometry. A layer of low-bandgap TiSi2 particles was deposited onto a titanium substrate followed by a second layer of TiO2 nanoparticles. The structure was then sintered at 600°C for 3 hours to promote TiSi2 interparticle necks and TiO2 densification. In the second method, sintered core-shell particles were produced using a novel four-electrode electrospray mixing device consisting of two opposing, oppositely energized hypodermic needle electrodes and two induction electrodes. The core-shell structure was verified by electrospraying fluorescent polystyrene latex spheres, and core-shell photoanodes were produced by encapsulating micron-sized TiSi2 particles with TiO2 nanoparticles. Cross-sections of the photoanodes were analyzed through microscopy and energy dispersive x-ray spectroscopy to reveal the resulting structure. COMMITTEE: Advisor: Malay K. Mazumder, MSE/ECE; Srikanth Gopalan, MSE/ME