Abstract
Hierarchical structured TiO2nanotubes were prepared by mechanical ball milling of highly ordered TiO2nanotube arrays grown by electrochemical anodization of titanium foil. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, specific surface area analysis, UV-visible absorption spectroscopy, photocurrent measurement, photoluminescence spectra, electrochemical impedance spectra, and photocatalytic degradation test were applied to characterize the nanocomposites. Surface area increased as the milling time extended. After 5 h ball milling, TiO2hierarchical nanotubes exhibited a corn-like shape and exhibited enhanced photoelectrochemical activity in comparison to commercial P25. The superior photocatalytic activity is suggested to be due to the combined advantages of high surface area of nanoparticles and rapid electron transfer as well as collection of the nanotubes in the hierarchical structure. The hierarchical structured TiO2nanotubes could be applied into flexible applications on solar cells, sensors, and other photoelectrochemical devices.
Highlights
Compared with photocatalysis (PC), photoelectrocatalysis (PEC) is more efficient and effective
We reported the fabrication of hierarchical structured anatase TiO2 nanotubes in gram-scale via a facile two-step approach: highly ordered uniform TiO2 nanotube arrays were first grown by conventional electrochemical anodization of titanium foil, followed by mechanical ball milling
When the milling time was extended to 5 h, the surface morphology appeared to be uniform, and nanotubes were completely dispersed into individual ones and coated with nanoparticles homogeneously
Summary
Compared with photocatalysis (PC), photoelectrocatalysis (PEC) is more efficient and effective. Highly ordered TiO2 nanotube arrays (TNTAs) have been fabricated using a simple electrochemical anodization process and demonstrated to be with potential applications such as gas sensors [4], solar cells [5], photodegradation [6], and water splitting [7]. TiO2 nanotube arrays possess large internal surface area, direct electron transfer path, and low recombination rate [8,9,10,11], enabling us to achieve a higher photocatalytic activity and efficiency. Scheme 1: Illustration of the large surface area and efficient charge carrier collection as well as transfer in the hierarchical structured TiO2 nanotubes. The preferable photocatalytic activity can be attributed to the combined advantages of high surface area of nanoparticles and efficient charge carrier collection as well as fast electron transfer of the nanotubes in the hierarchical structure (as shown in Scheme 1). Besides the application in the formaldehyde detector in our previous report [14], hierarchical structured TiO2 nanotubes by this two-step method show superior photoelectrochemical properties
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