Insights into Interfacial Changes and Photoelectrochemical Stability of In(x)Ga(1-x)N (0001) Photoanode Surfaces in Liquid Environments
| Autor: | Leonhard Mayrhofer, Andreas Waag, Michael Moseler, Sönke Fündling, Andreas Hangleiter, Sònia Estradé, Mahmoud Abdelfatah, Hao Zhou, Heiko Bremers, Giulio Cocco, Gemma Martín, Matin Sadat Mohajerani, Lorenzo Caccamo, Wanja Dziony, G. Lilienkamp, Winfried Daum, Alaaeldin Gad, Francesca Peiró |
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| Rok vydání: | 2016 |
| Předmět: |
Photocurrent
Materials science Photoelectrochemistry Oxide Nanotechnology 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences chemistry.chemical_compound X-ray photoelectron spectroscopy chemistry Chemical engineering Transmission electron microscopy Solar light General Materials Science 0210 nano-technology Chemical composition Layer (electronics) |
| Zdroj: | ACS applied materialsinterfaces. 8(12) |
| ISSN: | 1944-8252 |
| Popis: | The long-term stability of InGaN photoanodes in liquid environments is an essential requirement for their use in photoelectrochemistry. In this paper, we investigate the relationships between the compositional changes at the surface of n-type In(x)Ga(1-x)N (x ∼ 0.10) and its photoelectrochemical stability in phosphate buffer solutions with pH 7.4 and 11.3. Surface analyses reveal that InGaN undergoes oxidation under photoelectrochemical operation conditions (i.e., under solar light illumination and constant bias of 0.5 VRHE), forming a thin amorphous oxide layer having a pH-dependent chemical composition. We found that the formed oxide is mainly composed of Ga-O bonds at pH 7.4, whereas at pH 11.3 the In-O bonds are dominant. The photoelectrical properties of InGaN photoanodes are intimately related to the chemical composition of their surface oxides. For instance, after the formation of the oxide layer (mainly Ga-O bonds) at pH 7.4, no photocurrent flow was observed, whereas the oxide layer (mainly In-O bonds) at pH 11.3 contributes to enhance the photocurrent, possibly because of its reported high photocatalytic activity. Once a critical oxide thickness was reached, especially at pH 7.4, no significant changes in the photoelectrical properties were observed for the rest of the test duration. This study provides new insights into the oxidation processes occurring at the InGaN/liquid interface, which can be exploited to improve InGaN stability and enhance photoanode performance for biosensing and water-splitting applications. |
| Databáze: | OpenAIRE |
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