The study of visible light active bismuth modified nitrogen doped titanium dioxide photocatlysts: Role of bismuth

► Bi/N-TiO2 nanoparticles were prepared by hydrothermal and impregnation method. ► Bi20TiO32/N-TiO2 composites were formed from 7 mol% Bi loading in relation to Ti. ► Bi4+ was doped in the sub-surface while Bi20TiO32 was dispersed on the surface. ► Bi/N-TiO2 degraded 2,4-DCP under visible light effectively. ► Bi species enhanced visible light harvesting, e−/h+ separation and mobility.