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O: Fachverband Oberflächenphysik

O 84: Focus Session: Semiconductor Materials and Nanostructure for Photocatalysis

O 84.3: Vortrag

Donnerstag, 23. März 2017, 10:15–10:30, POT 51

Semiconductor surface stabilization under photoelectrochemical conditions — •Waqas Saddique, Klaus Stallberg, Gerhard Lilienkamp, and Winfried Daum — Institute of Energy Research and Physical Technologies, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld, Germany

The production of hydrogen by solar energy via water splitting in photoelectrochemical (PEC) cells is a field of current research and challenges in materials research. III-V semiconductors with suitable band gaps are candidates for water splitting but frequently subjected to corrosion during the water splitting process and suffer from corrosion-related decrease in efficiency. GaP has an indirect band gap of 2.26 eV which covers both the hydrogen and oxygen evolution potentials. So GaP can in principle be used as photocathode and photoanode, respectively. We have studied structural and chemical properties and modifications of an n-GaP(100) photoanode after extended photoelectrochemical activity. A 4 nm thin oxide film was produced at the surface of an n-GaP(100) photoanode via oxidizing the surface at specific PEC conditions and subsequently hydrogenating the surface to passivate defects in the oxide film. This specific process results in the formation of a stable Ga surface oxide, which inhibits corrosion while allowing the light and the charge carriers to pass through the thin oxide for the completion of the PEC process. No other prior surface treatments or catalysts were required for this process. An open-circuit potential Voc of 1.2 V vs the reversible hydrogen electrode (RHE) was also determined.