Enhancing visible-light-induced photocatalytic activity by coupling with wide-band-gap semiconductor: A case study on Bi2WO6/TiO2

The composites of different semiconductors based on the nanoscale coupling effect for photocatalytic application has been a challenging yet very important research topic. Bi2WO6 and TiO2, the two most extensively studied photocatalysts, were successfully coupled via a facile one-step hydrothermal process. The as-prepared Bi2WO6/TiO2 possessed enhanced visible-light-induced activity in photocatalytic degradation of contaminants in aqueous/gaseous phases compared with those of the sole Bi2WO6 or TiO2. The versatile Bi2WO6/TiO2 photocatalyst also exhibited long-time recyclable ability for the contaminants degradation under visible irradiation (lambda > 420 nm) of Xenon lamp or household fluorescent lamp. The photoluminescence and electrochemical impedance spectroscopy are both adopted to analyze the physical properties of the photogenerated carriers and it was found that the separation of photogenerated carriers of Bi2WO6 has been largely promoted after being coupled with wide-band-gap semiconductor TiO2. This work could be extended to the design of other composite photocatalyst with the purpose of enhancing activity by coupling suitable wide and narrow band-gap semiconductors, which is inspiring for the practical environmental purification. (C) 2011 Elsevier B.V. All rights reserved.