Iodine-modified　TiO2　nanocrystallites　(denoted　as　I-TiO2)　were　synthesized　by　a　combination　of　sol-gel　process　(TiO2　sol)　and　solvothermal　method　in　the　presence　of　HI　solution.　Their　photocatalytic　and　anti-bactericidal　activities　were　systematically　investigated　under　visible　light　irradiation.　The　results　showed　that　the　iodine　modifier　existed　in　the　form　of　I2　is　responsible　for　the　visible　light　response.　Moreover,　the　I2　significantly　enhanced　the　antibacterial　activity　under　visible　light　and　was　stable　during　the　photocatalytic　process.　In　addition,　an　interesting　post-illumination　catalytic　memory　of　I-TiO2　that　continues　to　inhibit　the　growth　of　Escherichia　coli　in　dark　was　also　observed　after　the　visible　light　was　shut　off.　©　2015　Elsevier　B.V.