Carbon-doped　g-C3N4　was　synthesized　using　a　simple　high-temperature　process　(calcination　at　550　°C　for　4　h).　One-dimensional　nanofibrillated　cellulose　(NFC)　materials　were　then　inserted　into　the　two-dimensional　g-C3N4　material　by　vacuum　filtration　method　at　room　temperature.　The　prepared　g-C3N4/NFC　composite　membranes　were　systematically　characterized　using　a　series　of　techniques,　such　as　XRD,　FTIR,　and　SEM.　The　results　showed　that　the　carbon-doped　photocatalysts　possessed　a　narrow　band　gap,　which　prolonged　the　visible　light　absorption　and　favored　the　organic　pollutant　degradation.　The　incorporation　of　NFC　enlarged　the　interlayer　spacing,　leading　to　an　increase　in　the　water　flux.　The　water　flux　of　C0.02CN/NFC　(15%)　composite　membranes　reached　73.7　L•m-2•h-1•bar-1,　which　is　more　than　that　of　g-C3N4/NFC　membrane.　At　the　same　time,　the　carbon　doped　composite　membranes　showed　enhanced　retention　and　photocatalytic　degradation　ability.　The　retention　rate　of　the　C0.02CN/NFC　(5%)　composite　membranes　could　reach　89.3%　from　80.8%　after　three-cycle　photocatalytic　experiments.　The　membrane　maintained　a　good　retention　rate　and　feed　flux,　which　confirms　the　composite　membrane　has　good　self-cleaning　ability　and　stability.　It　could　potentially　be　applied　for　water　treatment.　©　2025,　North　Carolina　State　University.　All　rights　reserved.