Distribution-tunable growth of ZnO nanorods on the inner walls of microcapillaries from reverse micelle deriving seed patterns

A novel route to pattern microchannels of microfluidics devices utilizing ZnO micro/nanostructures was demonstrated. Firstly well-dispersed ZnO crystals were seeded on the inner walls of long silica microcapillaries through utilization of nanosized reverse micelles combining with an unconventional demulsification technique. Based on the as-prepared ZnO seeds, the flower-like clusters of ZnO nanorod arrays with controllable distribution density were obtained on the inner surface of the microcapillaries. By changing the molar ratio of water to cetyltrimethyl ammonium bromide and the concentration of reactants in the reverse micelles, distances among the seeds were well controlled which resulted in the controllable distribution density of the final ZnO nanorod arrays. We used the microcapillaries with ZnO nanorods as microreactors to photocatalyze methylene blue degradation. The photocatalytic property of the microreactors was influenced by the distribution density of the nanorods and the residence time in the microchannel. The results here present a new possibility for the formation of nanopatterns on surface of long microchannels. Moreover, further improvements of this approach are expected to result in unique architectures at the nanoscale in microchannels which is important for the development of functional integrated microfluidic devices. (C) 2009 Elsevier B.V. All rights reserved.