Postnitridation　annealing　has　a　remarkable　effect　on　the　surface　property　and　photocatalytic　performance　of　N-doped　TiO2　for　photocatalytic　oxidation　of　ethylene.　The　activity　of　N-doped　TiO2　under　visible　light　illumination　(lambda　＞　420　nm)　can　be　enhanced　fourfold　by　annealing　the　sample　at　400　degrees　C.　Characterization　results　show　that　the　thermal　annealing　reduces　surface　oxygen　vacancies,　removes　surface-adsorbed　NH3,　and　facilitates　the　adsorption　of　molecular　oxygen　on　catalyst　surface.　Such　a　surface　reconstruction　contributes　to　the　enhanced　photocatalytic　activity　of　the　N-doped　TiO2.　The　postcalcination　also　improves　the　photocatalytic　stability　of　the　N-doped　TiO2　by　stabilizing　nitrogen　atoms　in　the　TiO2　lattice.　A　N-doped　TiO2　sample　without　postcalcination　suffers　from　a　gradual　deactivation,　due　mainly　to　the　passivation　of　the　catalyst　surface　by　oxidized　nitrogen　species　(e.g.,　hyponitrite,　nitrite　ions,　and　nitrate　ions)　formed　during　the　photocatalytic　degradation　of　ethylene.　(c)　2008　Elsevier　Inc.　All　rights　reserved.