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. 2019 Sep 20;9(10):1347.
doi: 10.3390/nano9101347.

Fabrication of Durable Ordered Ta2O5 Nanotube Arrays Decorated with Bi2S3 Quantum Dots

Mateusz A Baluk  1 , Marek P Kobylański  2 , Wojciech Lisowski  3 , Grzegorz Trykowski  4 , Tomasz Klimczuk  5 , Paweł Mazierski  6 , Adriana Zaleska-Medynska  7
Affiliations

Fabrication of Durable Ordered Ta2O5 Nanotube Arrays Decorated with Bi2S3 Quantum Dots

Mateusz A Baluk et al. Nanomaterials (Basel). .

Abstract

One of the most important challenges in the fabrication of ordered tantalum pentaoxide (Ta2O5) nanotube arrays (NTs) via the electrochemical method is the formation of nanotubes that adhere well to the Ta substrate. In this paper, we propose a new protocol that allows tight-fitting Ta2O5 nanotubes to be obtained through the anodic oxidation of tantalum foil. Moreover, to enhance their activity in the photocatalytic reaction, in this study, they have been decorated by nontoxic bismuth sulfide (Bi2S3) quantum dots (QDs) via a simple successive ionic layer adsorption and reaction (SILAR) method. Transmission electron microscopy (TEM) analysis revealed that quantum dots with a size in the range of 6-11 nm were located both inside and on the external surfaces of the Ta2O5 NTs. The effect of the anodization time and annealing conditions, as well as the effect of cycle numbers in the SILAR method, on the surface properties and photoactivity of Ta2O5 nanotubes and Bi2S3/Ta2O5 composites have been investigated. The Ta2O5 nanotubes decorated with Bi2S3 QDs exhibit high photocatalytic activity in the toluene degradation reaction, i.e., 99% of toluene (C0 = 200 ppm) was degraded after 5 min of UV-Vis irradiation. Therefore, the proposed anodic oxidation of tantalum (Ta) foil followed by SILAR decorating allows a photocatalytic surface, ready to use for pollutant degradation in the gas phase, to be obtained.

Keywords: Bi2S3 quantum dots; heterogeneous photocatalysis; ordered Ta2O5 nanotubes.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Scanning electron microscope (SEM) images of nanotube arrays (NTs): the effect of (a) applied voltage, (b) annealing temperature, (c) anodization time, and (d) annealing duration, (e) annealing atmosphere on the morphology and adhesive properties of tantalum pentaoxide (Ta2O5) nanotubes.
Figure 2
Figure 2
X-ray photoelectron spectroscopy (XPS) spectra of nanotube array (NT)-modified bismuth sulfide (Bi2S3) quantum dots (QDs).
Figure 3
Figure 3
X-ray diffraction patterns for the Management Information Base (MIB) sample before (top) and after (bottom) the anodization process. Open circles represent experimental data, whereas the solid red line is a LeBail profile fit with two models used: Ta (Im-3m) and Ta4O (Pmmm) shown by black and blue vertical bars, respectively.
Figure 4
Figure 4
Scanning electron microscope (SEM) images and schematic representation of the surface of nanotube arrays (NTs) modified by quantum dots (QDs).
Figure 5
Figure 5
Transmission Electron Microscopy (TEM) images for nanotube arrays (NTs) modified by bismuth sulfide (Bi2S3) quantum dots (QDs).
Figure 6
Figure 6
Photocatalytic activity of selected samples, shown as toluene degradation: (a) photocatalyst stability during three irradiation cycles for NTs_15 V_5 min_N2_450 °C_1 h and NTs_15 V_5 min_N2_450 °C_1 h_QDs_SILAR 1x. (b) Efficiency of toluene removal over Ta2O5 nanotube arrays (NTs) and bismuth sulfide (Bi2S3) quantum dots (QDs)/Tantalum pentoxide (Ta2O5) NTs samples and in the blank tests (toluene photolysis in the absence of a photocatalyst) under monochromatic light—318 nm and 730 nm.
Figure 7
Figure 7
Proposed photodegradation mechanism for (a) nanotube arrays (NTs) and (b) NTs modified by quantum dots (QDs).
See this image and copyright information in PMC

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