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　(λ　>　420　nm)　can　be　enhanced　fourfold　by　annealing　the　sample　at　400　°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.　©　2008　Elsevier　Inc.　All　rights　reserved.