Defected TiO2 nano-powder was synthesized by applying NaBH4 assisted heat treatment (300-450 degrees C) on pristine TiO2 nanoparticles under argon atmosphere. By increasing the process temperature, higher defect percentage (oxygen vacancies) can be achieved. In line with the defect concentration, significant enhancement of absorption in visible light also observed. Further characterization reveal that the defect created via NaBH4 treatment is mainly bulk defect which trigger recombination of electrons and holes. The concentration of defect contributes to the photocatalytic activity. Controllable defect produced by NaBH4 reduction at 350 degrees C lead to the better photocatalytic activity performance of Rhodamine B degradation under simulated solar light. (C) 2017 Elsevier B.V. All rights reserved.