Photocatalytic activity enhancement of TiO 2 nanocrystalline thin film with surface modification of poly-3-hexylthiophen
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improve photocatalytic activity of TiO2, 3-hexylthiophene monomers were in situ polymerized on porous TiO2 nanocrystalline thin film. Poly-3-hexylthiophene (P3HT) was homogenously modified on the thin film. The surface modification amounts of P3HT were controlled using different concentrations of 3-hexylthiophene monomer ether solutions and detected by the absorption spectra. The photocatalytic performance tested in methyl orange solution under ultraviolet light irradiation was significantly enhanced due to the modification of P3HT. Within 210 min, approximately 80% of methyl orange was degraded for the modified film with the optimized modification amount, it is twice higher than that of the film without modification. Photoluminescence spectra and open-circuit voltage decay processes of the samples were measured to demonstrate the photocatalytic activity enhancement mechanism due to the in-situ polymerization of P3HT. The homogenous modification of P3HT can promote separation of photogenerated electron–hole pairs on the TiO2 nanocrystalline thin film, which suppresses the recombination of photogenerated charge carriers, thus improving its photocatalytic activity.
I. INTRODUCTION
Recently, semiconductor nanomaterials, due to their potential applications to deal with the problems of energy shortage and environment pollution, have attracted much attention of researchers in the world. They not only can be used in the fabrication of solar cells1 and hydrogen production by photocatalytic water splitting,2–4 but also be used as a photocatalyst to degrade organic and inorganic pollutants in the environment.5 As one of the most promising photocatalysts, TiO2 has catched much attention due to its high efficiency, chemical stability, easy availability, and non-toxicity, and was widely used in the photodegradation of environmental organic pollutants and the waste-water treatments.6–8 Searching for visible light activated titania has been an interesting topic because of its significance as a photocatalyst for environmental applications under solar irradiation.9 TiO2 used as a catalyst for the ambient light, however, has two major disadvantages. One is its wide band gap (3.2 eV), which can only be response to the proportion of less than 5% of the ultraviolet radiation in sunlight. So the direct use of solar energy is limited for TiO2 photocatalyst.10,11 Another one is the easy recombination of Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.124
photogenerated electron and hole, resulting in the decrease of photocatalytic activity, which is mainly decided by the separation process of photogenerated electron and hole pairs on TiO2. Many efforts have been attempted towards the reduction of photogenerated electron–hole recombination rate on TiO2.12,13 Several researchers reported that modification of noble metal, such as Au, Ag, Pt, and Ru, could promote the effective separation of electrons and holes.14–18 Noble metal deposited on TiO2 surface was thought to pr
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