Hierarchically structured, nanoparticle-on-nanofiber composite membranes were successfully prepared by electrospray of titanium dioxide (TiO2) suspensions and electrospinning of polyacrylonitrile (PAN) solution simultaneously. The results showed that the TiO2 nanoparticles were highly dispersed on the surface of PAN nanofibers to construct hierarchical nanostructures, which could not only endow the composite membrane with high photocatalytic activity but also further improve the filter efficiency of the composite membrane. Furthermore, the photocatalytic activities and filter efficiencies of composite membranes could be further tuned by controlling the TiO2/PAN mass ratios. Our study indicated that the combination of TiO2 nanoparticles and PAN nanofibers via simultaneous electrospinning-spray offers a new strategy to construct advanced multifunctional TiO2/PAN membranes with hierarchical nanostructures, which could not only perform well in decomposing toluene but also remove particulate matter in air effectively. (C) 2017 Elsevier Inc. All rights reserved.