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Microfluidic chip has been performed as a platform of various chemical reactions with high efficiency due to the large surface to volume ratio and shorter diffusion distance of reactant solution in microchannels1-3.In this work,we presented a novel microfluidic-based photocatalytic microreactor by using electrospun nanofibrous TiO2 as the photocatalyst.The micoreactor is simply fabricated by sealing the nanofibrous TiO2 between the polydimethylsiloxane (PDMS) substrate and glass slide.The photoreaction was carried out using methylene blue (MB) solution as pollutant under UV irradiation and the absorption spectra were analyzed by a UV spectrophotometer.The degradation rate of MB in fiber microreactor exhibited an increasing stage and a subsequent comparatively stable stage,which was due to photo-induced hydrophilicity.At the initial stage,the hydrophobicily of nanofibrous TiO2 inhibited the interaction with MB solution,but the hydrophilicity of nanofibrous TiO2 could increase gradually under UV irradiation,and then more MB infiltrated into the pores of nanofibrous TiO2 and contact with more nanofibrous TiO2,thus,leading to the increment of MB degradation.Further investigation of the photodegradation under different flow rates showed the increasing photocatalytic activity of fiber microreactor with elongation time of UV irradiation.This may due to that the nanofibrous TiO2 with interconnected pores could provide enough surface to contact with more reactant when the residence time was increasing.In conclusion,combining the advantages of fast diffusion rate in microfluidic channel and high special surface of nanofibrous photocatalyst,the fiber microreactor demonstrates much higher photocatalytic activity and exhibits a broad range of applications in photocatalysis field.