Capillary microchannel-based microreactors with highly durable ZnO/TiO2 nanorod arrays for rapid, high efficiency and continuous-flow photocatalysis

A novel, highly durable capillary-based photocatalytic microreactor containing TiO2 nanoparticle-coated ZnO nanorod arrays grown on the inner wall of the capillaries (IWC) was successfully constructed simply by pumping a TiO2 Sol into capillaries containing preformed ZnO nanorod arrays. Methylene blue was used as a model organic compound to evaluate the photocatalytic performance of the capillary microreactors (CMs). The CMs containing ZnO/TiO2 nanorod arrays showed higher photocatalytic performance than a CM containing only ZnO nanorods at the same residence time. The effect of the number of TiO2 sol coatings and the recyclable properties of the CM were investigated. These CMs showed rapid and highly efficient photocatalytic activities and the ZnO/TiO2 nanorod arrays displayed high durability during continuous recycling. The superior photocatalytic activity of the ZnO/TiO2 nanorod-modified CMs was attributed to the topographical morphology induced by the nanorod arrays, and the combination of two semiconductors decreasing the recombination rate of photoinduced electrons and holes. These CMs show the promising application of the photodegradation of organic pollutants. (C) 2009 Elsevier B.V. All rights reserved.