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Issue 7, 2017
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Interfacial study of Cu2O/Ga2O3/AZO/TiO2 photocathode for water splitting fabricated by pulsed laser deposition

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Abstract

Cuprous oxide (Cu2O) is expected to be one of the most promising materials for utilizing solar energy. One strategy comprises using Cu2O as a photocathode to obtain hydrogen by the reduction of water. However, the instability of Cu2O in solution hinders its employment to a great extent. Here, we fabricated a multilayer photocathode with the structure of Cu2O/Ga2O3/AZO/TiO2 by the pulsed laser deposition (PLD) technique. The highest photocurrent density was increased to 6.5 mA cm−2 in comparison to 4.5 mA cm−2 for bare Cu2O at 0 V versus a reversible hydrogen electrode (RHE), and the stability was also improved to some extent. The properties of Ga2O3 were affected to a great extent by the oxygen pressure, which thereby changed the photovoltage and stability of the photocathode. Alignment of band energies is introduced to explain this phenomenon. In a sample containing Ga2O3 under a low oxygen pressure, the relatively lower Fermi level and conduction band edge in the Ga2O3 layer formed a region of electron accumulation near the interface, which impaired its performance. In addition, the interfacial chemical state of copper element was investigated by X-ray photoelectron spectroscopy (XPS) in combination with Ar ion etching. It was revealed that for both samples Cu+ was reduced to Cu0 during the fabrication process near the Cu2O/Ga2O3 interface, which is harmful for stability. These factors resulted in the relatively unstable performance of the photocathode. This work reveals the performance of a multilayer photocathode grown by PLD and points out possible ways of improving it.

Graphical abstract: Interfacial study of Cu2O/Ga2O3/AZO/TiO2 photocathode for water splitting fabricated by pulsed laser deposition

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Publication details

The article was received on 08 Jan 2017, accepted on 06 Mar 2017 and first published on 07 Mar 2017


Article type: Paper
DOI: 10.1039/C7CY00040E
Citation: Catal. Sci. Technol., 2017,7, 1602-1610
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    Interfacial study of Cu2O/Ga2O3/AZO/TiO2 photocathode for water splitting fabricated by pulsed laser deposition

    W. Niu, L. Zhu, Y. Wang, Z. Lou and Z. Ye, Catal. Sci. Technol., 2017, 7, 1602
    DOI: 10.1039/C7CY00040E

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