A　new　synthetic　method　to　prepare　tantalum(v)　nitride　(Ta3N5)　nanoparticles　from　a　mesoporous　carbon　nitride　template　is　proposed;　the　Ta3N5　has　a　high　surface　area,　a　low　density　of　defect　sites,　and　shows　one　magnitude　higher　activity　than　the　bulk　Ta3N5　for　photocatalytic　hydrogen　evolution　under　visible　light　irradiation.