Preparation and characterization of polypyrrole/TiO 2 nanocomposite and its photocatalytic activity under visible light
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A simple and convenient method for preparing visible light response photocatalyst polypyrrole/TiO2 (PPy/TiO2) nanocomposite was developed. The products were characterized by x-ray diffraction, transmission electron microscopy, atomic force microscopy, ultraviolet-visible, and Fourier transform infrared techniques. The results indicated that the nanohybrid was composed of anatase TiO2 and PPy and exhibited an enhanced visible light-capturing ability. Average diameters of TiO2 and PPy/TiO2 were 18 and 35 nm, respectively. The photocatalytic activity of the nanocomposite was evaluated by the degradation of methyl orange under visible light irradiation. In the presence of PPy/TiO2 nanocomposite, the degradation efficiency of methyl orange of 95.54% could be obtained under visible light irradiation within 120 min. The apparent rate constant was 2.19 102, which was better than that Degussa P25 nano-TiO2. The sensitization mechanism of PPy/TiO2 photocatalyst was discussed briefly. I. INTRODUCTION
It has been demonstrated that semiconducting materials capable of mediating photocatalytic oxidation of organic compounds can be an alternative to conventional methods for the removal of organic pollutants from water.1 Advantages of the photocatalytic process include its mild operating conditions and the fact that it can be powered by visible light, thus significantly reducing the operating costs. Due to the strongly oxidizability, nontoxicity, and long-term photostability, nano-TiO2 exhibits many advantages over the other photocatalysts, even bulk of TiO2.2 However, there are still some shortcomings, such as the lack of a visible light response, a low quantum yield, and lower photocatalytic activity. To overcome these problems, some strategies have been investigated, including noble metal deposition, doping of metal or nonmetal ions, blending with another metal oxide, surface photosensitizing with dye, and compositing with polymer.3 Polypyrrole (PPy) is an especially promising conductive polymer for commercial applications, due to its high conductivity, good environmental stability, and ease in synthesis. Its use as new material has opened up an entirely new field for polymeric material.4 Furthermore, PPy is one of the most familiar conducting polymers that show many advantages in recombining nanomaterials compared with others. The large internal interface area in PPy/inorganic nanocomposite enables an efficient separation of charge, which is a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0316 J. Mater. Res., Vol. 24, No. 8, Aug 2009
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important for photovoltaic application. Therefore, intense research interests have been focused on the PPy/ inorganic nanocomposite.5 PPy/TiO2 nanocomposite combines the merits of PPy and nano-TiO2 to develop the potential applications in many fields. Some studies on the optical and electronic properties of PPy/TiO2 nanocomposite have been reported in recent years.6 To the best of our knowledg
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