©　2018　Elsevier　B.V.　Fabrication　of　photocatalysis　films　with　good　adhesion,　hydrophilicity,　and　high　activity　on　substrates　at　room　temperature　is　essential　for　their　application　in　air　pollution　control.　Herein,　functionalized　transparent　composite　films　containing　ultrathin　protonated　g-C3N4　(pCN)　nanosheets　and　Ti3+　self-doped　TiO2　nanoparticles　(pCN/TiO2)　were　fabricated　on　glass　at　room　temperature.　Thickness　of　the　films　measures　80　nm　with　surface　roughness　of　7.16　nm.　The　adhesion　ability　was　attributed　to　the　viscosity　of　TiO2　sol,　which　served　as　“chemical　glue”　in　the　films.　The　high　photo-induced　hydrophilicity　demonstrated　their　self-cleaning　potential.　pCN/TiO2　films　showed　remarkably　high　visible-light-driven　activity　in　terms　of　NO　removal　in　a　continuous-flow　mode.　Photoelectrochemical　tests　demonstrated　the　superior　charge　separation　efficiency　of　pCN/TiO2　films　compared　with　that　of　pristine　TiO2.　As　identified　by　electron　spin　resonance　spectra,　[rad]O2　−　and　[rad]OH　radicals　were　the　key　reactive　species　involved　in　NO　removal.　The　possible　mechanism　for　photocatalytic　NO　oxidation　was　proposed.　Potential　cytotoxicity　of　pCN/TiO2　films　was　evaluated　by　3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium　bromide　assay　to　ensure　the　biosecurity.　This　work　provides　a　facile　route　to　fabricate　nanocomposite　films　under　ambient　temperature.　The　nanocomposite　films　were　characterized　by　photo-induced　hydrophilicity,　high　NO　removal　efficiency,　and　good　biocompatibility,　showing　its　potential　in　large-scale　application.