The　combination　of　photocatalyst　with　cementitious　materials　for　air　pollution　abatement　and　self-cleaning　has　gained　considerable　attention.　However,　the　most　popularly　used　photocatalytic　cementitious　composites　based　on　TiO2　achieve　the　purification　function　under　ultraviolet　sunlight,　significantly　impeding　a　broader　application　of　photocatalytic　cementitious　composites.　Here,　the　photocatalytic　cementitious　composites　were　prepared　by　incorporating　g-C3N4　nanosheets　(CNNs)　in　Portland　cement.　With　the　increase　of　CNNs　content,　the　photocatalytic　NOx　abatement　and　self-cleaning　performance　was　notably　improved,　while　the　micro-hardness　of　cementitious　composites　increased　first　and　then　decreased.　Among　the　three　mixing　dosages　(0.5%,　1%　and　2%　by　weight　of　cement),　the　cementitious　composite　admixed　with　2%　CNNs　showed　the　highest　photocatalytic　NOx　abatement　efficiency　of　227.3　μmol　m−2　h−1,　and　could　degrade　the　rhodamine　B　within　40　min　under　visible　light.　Additionally,　its　microscopic　hardness　was　5.4%　higher　than　the　one　without　CNNs,　suggesting　that　a　moderate　amount　of　CNNs　(below　2%)　in　cementitious　composites　was　effective　in　achieving　an　improved　photocatalytic　depollution　performance.　©　2019　Elsevier　Ltd