Synthesis and investigation of TiO 2 nanotube arrays prepared by anodization and their photocatalytic activity Hailei Li, Lixin Cao * , Wei Liu, Ge Su, Bohua Dong Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province, PR China Received 23 March 2012; received in revised form 8 April 2012; accepted 9 April 2012 Available online 14 April 2012 Abstract TiO 2 nanotube arrays were successfully prepared by anodic oxidation method in the electrolyte of ethylene glycol and deionized water mixed in 9:1 volumetric ration including 0.5 wt.% NH 4 F. The microstructure and phase compositions of samples annealing from 0 8C to 800 8C were characterized by field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). FESEM showed that the obtained nanotubes with diameter 80–100 nm and length 4.89 mm were highly ordered and perpendicular to Ti substrate. The tubular structure collapsed at 680 8C. The photocatalytic activity of samples annealing at different temperature were calculated by the degradation of a model dye, methyl orange (MO), under UV light illumination. The results indicated the phase composition and the morphology of TiO 2 nanotubes both played an important role in the degradation of MO. In addition, the effects of initial solution pH and dye concentration on degradation of MO had also been investigated. As a result, the optimum values of calcination temperature, initial solution pH and dye concentration were found to be 550 8C, 3, 10 mg/l, respectively. The best photodegradation of MO was 76% under illumination for 3 h. # 2012 Published by Elsevier Ltd and Techna Group S.r.l. Keywords: TiO 2 nanotube arrays; Anodic oxidation; Photocatalytic reaction; Methyl orange 1. Introduction As an important inorganic functional material, TiO 2 has been widely used in applications of dye-sensitized solar cells (DSSC), environmental purification, water splitting, gas sensor bio-application, optical and photonic [1–10] due to its excellent dielectric effect, photoelectric conversion and superior photo- catalytic properties. In the past few years, TiO 2 nanoparticles as traditional photocatalyst have been used to photodegradate the organic pollutants. But to overcome their some drawbacks of low surface area, easy aggregation during reaction and difficult separation after reaction, high recombination efficiency of photogenerated electron–hole pairs, several methods for fabricating the fixed TiO 2 photocatalyst on solid support substrates have been studied, including sol–gel method [11], laser calcination [12], template synthesis [13], sputtering [14] and anodic oxidation [15]. Among these preparations, highly ordered TiO 2 nanotube arrays growing directly on Ti substrate are fabricated by anodic oxidation which is simplicity in operation and easy control in the synthesis. Zwilling et al. [16] first fabricated TiO 2 in the form of hollow nanotubes on titanium alloy by anodic oxidation method, and in 2001, G.K. Mor et al. [17] reported that the uniform TiO 2 nanotube arrays were synthesized on a pure titanium sheet using the same method. Following then, preparation parameters influencing on the structure of TiO 2 nanotube arrays had been reported. These various parameters concluded electrolyte composition, the anodic voltage, time and pH. Furthermore, attention also had been paid to the effect of TiO 2 nanotubes structure and phase composition on photodegradation of pollutants. However, the results were not consistent with each other. For example, Liang and Li [18] reported that TiO 2 nanotubes with a mixed phase of anatase/rutile had a better photocatalytic activity. Whereas, Fang et al. [19] claimed that TiO 2 nanotubes with a pure anatase phase obtained a better photocatalytic activity. Therefore, it is still worthy of paying attention to improvement of photocatalytic activity of TiO 2 nanotube arrays. In this paper, the aim of our study was focused on the photocatalytic activity of TiO 2 nanotube arrays fabricated by www.elsevier.com/locate/ceramint Available online at www.sciencedirect.com Ceramics International 38 (2012) 5791–5797 * Corresponding author. Tel.: +86 532 66781901; fax: +86 532 66781320. E-mail address: [email protected](L. Cao). 0272-8842/$36.00 # 2012 Published by Elsevier Ltd and Techna Group S.r.l. http://dx.doi.org/10.1016/j.ceramint.2012.04.026
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Synthesis and investigation of TiO2 nanotube arrays prepared by anodization and their photocatalytic activity Hailei Li, Lixin Cao *, Wei Liu, Ge Su, Bohua Dong
TiO2 nanotube arrays were successfully prepared by anodic oxidation method in the electrolyte of ethylene glycol and deionized water mixed in 9:1 volumetric ration including 0.5 wt.% NH4F. The microstructure and phase compositions of samples annealing from 0 8C to 800 8C were characterized by field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). FESEM showed that the obtained nanotubes with diameter 80–100 nm and length 4.89 mm were highly ordered and perpendicular to Ti substrate. The tubular structure collapsed at 680 8C. The photocatalytic activity of samples annealing at different temperature were calculated by the degradation of a model dye, methyl orange (MO), under UV light illumination. The results indicated the phase composition and the morphology of TiO2 nanotubes both played an important role in the degradation of MO. In addition, the effects of initial solution pH and dye concentration on degradation of MO had also been investigated. As a result, the optimum values of calcination temperature, initial solution pH and dye concentration were found to be 550 8C, 3, 10 mg/l, respectively. The best photodegradation of MO was 76% under illumination for 3 h. # 2012 Published by Elsevier Ltd and Techna Group S.r.l.
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Synthesis and investigation of TiO2 nanotube arrays prepared by
anodization and their photocatalytic activity
Hailei Li, Lixin Cao *, Wei Liu, Ge Su, Bohua Dong
Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province, PR China
Received 23 March 2012; received in revised form 8 April 2012; accepted 9 April 2012
Available online 14 April 2012
Abstract
TiO2 nanotube arrays were successfully prepared by anodic oxidation method in the electrolyte of ethylene glycol and deionized water mixed in
9:1 volumetric ration including 0.5 wt.% NH4F. The microstructure and phase compositions of samples annealing from 0 8C to 800 8C were
characterized by field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). FESEM showed that the obtained nanotubes
with diameter 80–100 nm and length 4.89 mm were highly ordered and perpendicular to Ti substrate. The tubular structure collapsed at 680 8C. The
photocatalytic activity of samples annealing at different temperature were calculated by the degradation of a model dye, methyl orange (MO),
under UV light illumination. The results indicated the phase composition and the morphology of TiO2 nanotubes both played an important role in
the degradation of MO. In addition, the effects of initial solution pH and dye concentration on degradation of MO had also been investigated. As a
result, the optimum values of calcination temperature, initial solution pH and dye concentration were found to be 550 8C, 3, 10 mg/l, respectively.
The best photodegradation of MO was 76% under illumination for 3 h.
# 2012 Published by Elsevier Ltd and Techna Group S.r.l.