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Insightful studies of AuCu nanostructures exhibiting improved photoactivity.
Researchers from the Laboratory of Functional Materials (Institute of Fluid-Flow Machinery Polish Academy of Sciences) studied the chemical nature of AuCu nanostructures deposited on Ti platform by X-ray absorption spectroscopy and X-ray photoelectron spectroscopy using synchrotron radiation. For the first time, synchrotron radiation based investigations of AuCu nanostructures were conducted in order to describe details of the material structure fabricated during rapid thermal annealing in various atmospheres and its impact onto the photoelectrochemical activity.
Nowadays, due to global warming and increasing environmental pollution, intensified research on materials for energy harvesting from renewable sources is being carried on. Solar energy is one of the most abundant energy resources that can be converted into electricity. In the article the researchers demonstrate that AuCu bimetallic nanostructures formed on nanostructured titanium foil can be applied as photoanode. The influence of various atmospheres (air, vacuum, argon, hydrogen) used during rapid thermal treatment on AuCu nanostructures was examined in terms of photoelectrochemical activity under visible and UV-vis light illumination. Changes in the chemical structure were investigated by X-ray absorption spectroscopy (Figure 1b) and X-ray photoelectron spectroscopy using synchrotron radiation provided the PHELIX beamline at the National Synchrotron Radiation Centre SOLARIS. Synchrotron studies enable an inspection within three zones (Figure. 1a) such as upper surface layer (2-3 nm), deeper surface layer (5-7 nm) and bulk (12-15 nm).
It was confirmed that the best photoelectrochemical activity under visible light was obtained for bimetallic AuCu electrodes annealed in hydrogen atmosphere (Figure 1c). For hydrogenated AuCu nanostructures deposited on Ti platform metallic gold was detected in the upper and deeper surface layers as well as in bulk whereas AuCu alloy only in deeper surface layer. Copper and copper oxides were detected in the upper and deeper surface layer where the amount of Cu2O was ca. 2 times higher in the upper layer than in deeper layer. Titanium dioxide was present on any depth. Taking into account gathered results can be stated that the presence of such Cu2O oxides in the upper layer is mostly responsible for extending activity under visible light illumination. It was concluded that hydrogenation has a positive effect on photoresponse by efficient acceptor–donor configuration of AuCu doping on/into TiO2 semiconductor showing its promising application in the field of light photoconversion.
Figure.1 a) Schematic representation of nanomaterial zones, b) XAS spectra of AuCu nanostructures deposited on Ti platform for Cu L-edges, c) linear voltammetry curves for AuCu-decorated Ti electrodes registered under visible light illumination.
Written by: Wiktoria Lipińska
Link to the publication:
Lipińska W., Bielan Z., Witkowska A., Karczewski J., Grochowska K., Partyka-Jankowska E., Sobol T., Szczepanik M. , Siuzdak K., Insightful studies of AuCu nanostructures deposited on Ti platform: Effect of rapid thermal annealing on photoelectrochemical activity supported by synchrotron radiation studies, Applied Surface Science, Volume 638, 30 November 2023, 158048 doi.org/10.1016/j.apsusc.2023.158048
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