Influence　of　defect　on　photocatalyst　is　in　extensive　concern.　In　the　present　contribution,　by　cold　plasma　treatment　(CPT)　technique　and　dip-coating　method,　we　successfully　prepared　ZnO　bilayer　films　with　oxygen　vacancies　and　interstitial　zinc　atoms.　The　defective　films　showed　promoted　photocatalytic　activity,　with　enhanced　transportation　and　good　separation　of　photogenerated　charge　carriers　being　the　main　reasons.　More　importantly,　combination　of　CPT　and　dip　coating　method　allowed　us　to　investigate　the　dominance　of　defect　and　its　stability.　Our　work　may　not　only　provide　helpful　information　for　better　understanding　of　relationship　between　defect　and　photocatalysis,　but　also　offer　a　new　strategy　for　designing　stabilized　defect-modulated　photocatalyst.　(c)　2013　Elsevier　B.V.　All　rights　reserved.