| Abstract Scope |
Photoelectrochemical water splitting carries out solar energy conversion into hydrogen, allowing to store chemical energy. n-type GaAs is an almost ideal photoanode for water oxidation, due to its optimal bandgap that absorbs a large fraction of the solar spectrum, while providing a larger photovoltage in comparison to silicon. The major drawback of GaAs is its instability in water and under illumination, leading to dissolution or oxidation. To avoid this limitation, a thin protective layer is necessary. In particular, self-limiting electrodeposition of iron group metals or alloys enables the formation of nanosized islands with high density, allowing for a dense, continuous film at a thickness of few nm. In this effort, galvanostatic electrodeposition was chosen to grow thin mutual Fe group alloys on GaAs substrate. XPS shows that the protective layers are metal oxyhydroxides; in addition, depth profiling measurements evidence that the electrodeposited film thickness is independent of deposition time. |