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Solar Hydrogen Generation with Wide-Band-Gap Semiconductors: GaP(100) Photoelectrodes and Surface Modification

Kaiser, Bernhard and Fertig, Dominic and Ziegler, Jürgen and Klett, Joachim and Hoch, Sascha and Jaegermann, Wolfram (2012):
Solar Hydrogen Generation with Wide-Band-Gap Semiconductors: GaP(100) Photoelectrodes and Surface Modification.
In: ChemPhysChem, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, pp. 3053-3060, 13, (12), ISSN 14394235, [Online-Edition: http://dx.doi.org/10.1002/cphc.201200432],
[Article]

Abstract

GaP, with its large band gap of 2.26 eV (indirect) and 2.78 eV (direct), is a very promising candidate for direct photoelectrochemical water splitting. Herein, p-GaP(100) is investigated as a photocathode for hydrogen generation. The samples are characterized after each preparation step regarding how their photoelectrochemical behavior is influenced by surface composition and structure using a combination of electrochemical and surface-science preparation and characterization techniques. The formation of an Ohmic back contact employing an annealed gold layer and the removal of the native oxides using various etchants are studied. It turns out that the latter has a pronounced effect on the surface composition and structure and therefore also on the electronic properties of the interface. The formation of a thin Ga2O3 buffer layer on the p-GaP(100) surface does not lead to a clear improvement in the photoelectrochemical efficiency, neither do Pt nanocatalyst particles deposited on top of the buffer layer. This behavior can be understood by the electronic structure of these layers, which is not well suited for an efficient charge transfer from the absorber to the electrolyte. First experiments show that the efficiency can be considerably improved by employing a thin GaN layer as a buffer layer on top of the p-GaP(100) surface.

Item Type: Article
Erschienen: 2012
Creators: Kaiser, Bernhard and Fertig, Dominic and Ziegler, Jürgen and Klett, Joachim and Hoch, Sascha and Jaegermann, Wolfram
Title: Solar Hydrogen Generation with Wide-Band-Gap Semiconductors: GaP(100) Photoelectrodes and Surface Modification
Language: English
Abstract:

GaP, with its large band gap of 2.26 eV (indirect) and 2.78 eV (direct), is a very promising candidate for direct photoelectrochemical water splitting. Herein, p-GaP(100) is investigated as a photocathode for hydrogen generation. The samples are characterized after each preparation step regarding how their photoelectrochemical behavior is influenced by surface composition and structure using a combination of electrochemical and surface-science preparation and characterization techniques. The formation of an Ohmic back contact employing an annealed gold layer and the removal of the native oxides using various etchants are studied. It turns out that the latter has a pronounced effect on the surface composition and structure and therefore also on the electronic properties of the interface. The formation of a thin Ga2O3 buffer layer on the p-GaP(100) surface does not lead to a clear improvement in the photoelectrochemical efficiency, neither do Pt nanocatalyst particles deposited on top of the buffer layer. This behavior can be understood by the electronic structure of these layers, which is not well suited for an efficient charge transfer from the absorber to the electrolyte. First experiments show that the efficiency can be considerably improved by employing a thin GaN layer as a buffer layer on top of the p-GaP(100) surface.

Journal or Publication Title: ChemPhysChem
Volume: 13
Number: 12
Publisher: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Uncontrolled Keywords: catalysis, hydrogen, materials science, semiconductors, solar energy
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Zentrale Einrichtungen
Exzellenzinitiative > Clusters of Excellence > Center of Smart Interfaces (CSI)
Exzellenzinitiative
Exzellenzinitiative > Clusters of Excellence
Date Deposited: 25 Nov 2013 09:23
Official URL: http://dx.doi.org/10.1002/cphc.201200432
Identification Number: doi:10.1002/cphc.201200432
Funders: Funded by BMBF, Grant Number: 03SF0353E
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