M.Sc Thesis


M.Sc StudentMoran Koren )Gross(
SubjectThe Influence of Gold Nanoparticles on the Optical and
Photoelectrochemical Properties of Iron Oxide
(alfa-Fe203) Photoanodes for Water
Splitting
DepartmentDepartment of Materials Science and Engineering
Supervisor Professor Rothschild Avner


Abstract

Hematite (a-Fe2O3) photoanodes convert solar power to hydrogen fuel by water photoelectrolysis. To overcome the challenge arising from the mismatch between short collection length of minority charge carriers and long light absorption length, different photon management schemes are examined. Encouraging results showing enhanced absorption in hematite thin films decorated with Au nanoparticles (NPs) were reported, but the gain in the water photo-oxidation currents falls short of the optical gain in light absorption. Furthermore, the root cause for the apparent photocurrent gain is unclear. This work examines the effect of Au NPs on the optical and photoelectrochemical properties of hematite thin films deposited by pulsed laser deposition on FTO-coated glass substrates. Au NPs of different diameters were obtained by dewetting of Au films. The Au NPs were embedded below the hematite films or placed on top of them. The embedded configuration displayed enhanced photocurrent by as much as 30%, under simulated solar radiation, with respect to the Au-free films. The enhancement was observed close to the photocurrent onset potential, fading out at higher potentials. Based on these findings we conclude that the enhancement is mostly due to catalytic rather than plasmonic effect. The on-top configuration displayed corrosion characteristics that are atypical for hematite photoanodes. Similar characteristics were observed in pristine Au electrodes, indicating that they arise from Au oxidation.