In this paper, flexible carbon nanofiber embedded with TiO2 (CNF/TiO2) was prepared by electrospinning technique, and used as negative electrode for vanadium redox flow battery (VRFB). CNF/TiO2 composites were synthesized from solution consisting of Ti(OC4H9)(4) as TiO2 precursor and polyacrilonitrile (PAN) as carbon precursor. High-purity rutile TiO2 can be dispersed evenly in CNF with the diameter of 100 -200 nm. CNF/TiO2 composites exhibited superior electrochemical activity towards V2+/V3+ redox reaction compared with pristine CNF. The excellent energy storage performances of VRFB were achieved via using CNF/TiO2 as negative electrode, with larger capacity and efficiency. At a current density of 90 mA cm(-2), the discharge capacity of the cell using CNF/TiO2 electrode reached 84.0 mA h, 48.5 mA h higher than that of pristine cell. The energy efficiency of the cell based on CNF/TiO2 increased by 8.7% compared with pristine cell. The excellent electrochemical performance of CNF/TiO2 composite towards V2+/V3+ redox reaction was attributed to the synergistic effect between carbon nanofiber networks with high conductivity and rutile TiO2 with high electrocatalytic properties. (c) 2018 Elsevier Ltd. All rights reserved.