Influence of Annealing Atmospheres on Photoelectrochemical Activity of TiO₂ Nanotubes Modified with AuCu Nanoparticles

Abstract

In this article, we studied the annealing process of AuCu layers deposited on TiO2 nanotubes (NTs) conducted in various atmospheres such as air, vacuum, argon, and hydrogen in order to obtain materials active in both visible and UV–vis ranges. The material fabrication route covers the electrochemical anodization of a Ti plate, followed by thin AuCu film magnetron sputtering and further thermal treatment. Scanning electron microscopy images confirmed the presence of spherical nanoparticles (NPs) formed on the external and internal walls of NTs. The optical and structural properties were characterized using UV–vis, X-ray diffraction, and X-ray photoelectron spectroscopies. It was proved that thermal processing under the argon atmosphere leads to the formation of a CuAuTi alloy in contrast to materials fabricated in air, vacuum, and hydrogen. The electrochemical measurements were carried out in NaOH using cyclic voltammetry, linear voltammetry, and chronoamperometry. The highest photoactivity was achieved for materials thermally treated in the argon atmosphere. In addition, the Mott–Schottky analysis was performed for bare TiO2 NTs and TiO2 NTs modified with gold copper NPs indicating a shift in the flatband potential. Overall, thermal processing resulted in changes in optical and structural properties as well as electrochemical and photoelectrochemical activities.

Interaction between bilirubin oxidase and Au nanoparticles distributed over dimpled titanium foil towards oxygen reduction reaction

“…Also, with the significant decrease of NP diameter deposited on TiO2/Ti substrate, the electrochemical features arising on CV scans tend to semiconductor behavior. Indeed, in our experimental conditions, TiO2 layer which is present between gold nanostructures is expected to interact more significantly with the smallest NPs [34,35]. Not only such a configura tio n might induce an underestimated surface, but it is expected to impact the reactivity of AuNPs as further demonstrated below.…”

Recent advances in anodically fabricated amorphous TiO2 nanotubes crystallization techniques and their applications

“…The anodically prepared TiO 2 nanotubes are amorphous kind in their nature. They are crystallized by annealing process in the temperature range of 400 -800 °C [30][31][32][33][34][35]. Typically, a muffle or box furnace is employed for heating purposes in air environment.…”

“…In the context of heating, in the presence of atmospheric oxygen/ nitrogen/argon, a tubular furnace is employed. The cylindrical shape of the tube facilitates enhanced precision and fast regulation of temperature and gas flow [24][25][26][27][28][29][30][31][32][33][34][35] (figure 4).…”

Annealing Rate as a Crucial Parameter Controlling the Photoelectrochemical Properties of AuCu Mosaic Core–Shell Nanoparticles

“…Furthermore, it was also outlined that thermal treatment of TiO 2 nanotubes modified by AuCu the magnetron‐sputtered layer in air, vacuum, argon, or hydrogen atmosphere has a great impact on the chemical structure and electrochemical activity of AuCu‐modified electrodes. [ 10 ] Thermal processing under argon leads to the formation of AuCuTi alloy, having increased donor concentration, defects as well as electron mobility, and improves the photocurrent in contrast to materials fabricated in air, vacuum, or hydrogen. Reports on the AuCu/nanopatterned Ti bimetallic structures indicate a synergetic effect compared to pure gold or copper oxides.…”