Si-modified alpha-Fe2O3 with small nanoparticle size has been synthesized by a simple one-pot water-organic separated hydrolysis-solvothermal method. It is demonstrated the modification with an appropriate amount of silicon obviously prolongs the lifetime and promotes the separation of photogenerated charge carriers of resulting alpha-Fe2O3, well responsible for the much high photocatalytic activity for degrading acetaldehyde and phenol under visible illumination compared with the unmodified one. It is suggested that the prolonged lifetime and promoted separation of photogenerated charges are attributed to the decreased nanocrystallite size and to the enhanced O-2 adsorption. Interestingly, the lifetime and separated situation of photogenerated charges of Si-modified Fe2O3 are further increased after thermal treatment at a proper high temperature, leading to the further enhancement of its visible photocatalytic activity. This mainly results from the increased crystallinity of Fe2O3 favorable to transport charge, and the slightly increased nanocrystallite size because of SiO2 introduction. (C) 2013 Elsevier Ltd. All rights reserved.