AuCu Nanostructures Active in the Visible Light – Optical and Photoelectrochemical Properties

Abstract

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 electric energy. Here, we demonstate that AuCu bimetallic nanostructures placed on structured titanium foil can be applied in solar driven processes [1, 2].The electrode material is fabricated via Ti foil anodization process, chemical etching, thin AuCu layer (10 nm) magnetron sputtering and rapid thermal treatment at 600°C in varius atmospheres (air, vacuum, argon, hydrogen). AuCu nanoparticles are obtained only for annealing in air, while in argon and hydrogen porous structures and nanoplates are formed, respectively. UV-vis spectroscopy and X-ray diffraction studies of marterials indicate that the shape of the reflectance spectra differ significantly due to the changes in material morphology as well as its structure. The reflectance band minima are located at 380 nm and 750 nm for electrode material annealed in air and hydrogen, respectivetly. Moreover, sample thermally treated in air exhibits wide absorbance band from 300 to 1000 nm, whereas the one annealed in hydrogen from 500 to 1000 nm. Linear voltammetry measurements in dark and under light illumination were carried out in 0.1M NaOH solution in order to evaluate the photoactivity. The highest photocurrent in visible light is obtained for AuCu electrode annealed in hydrogen (5 times higher than in air), however, under Uv-vis light for electrode processed in air.All in all, thermal treatment in various atmospheres has a great impact on morphology, optical and photoelectrochemical activity of AuCu structures placed on Ti support material. We believe that presented results provide new opportunities in designing advanced photoactive materials.Research is financed by National Science Centre (Poland): Grant no. 2019/35/N/ST5/02604.[1] W. Lipińska, K. Grochowska, J. Ryl, J. Karczewski, K. Siuzdak, Influence of Annealing Atmosphere on Photoelectrochemical Activity of TiO2 Nanotubes Modified with AuCu Nanoparticles, ACS Applied Materials and Interfaces, 13 (2021) 52967–52977, DOI: 10.1021/acsami.1c16271[2] W. Lipińska, K. Grochowska, J. Karczewski, J. Ryl, A. Cenian, K. Siuzdak, Thermally tuneable optical and electrochemical properties of Au-Cu nanomosaic formed over the host titanium dimples, Chemical Engineering Journal, 399 (2020) 125673–125685, DOI: 10.1016/j.cej.2020.125673 Figure 1