Controllable fabrication of Bi2O3/TiO2 heterojunction with excellent visible-light responsive photocatalytic performance

Three-dimensional Bi 2 O 3 /TiO 2 hierarchical composites have been successfully prepared by a two-step hydrothermal method and subsequent calcination. The samples were characterized using XRD, SEM, TEM, EDS, BET and DRS. The measurement results signified that heterojunctions of various morphologies β -Bi 2 O 3 growing on the three-dimensional hierarchical anatase TiO 2 nanorods arrays on FTO glass were apparently formed. The morphology of Bi 2 O 3 changed from three-dimension flower-like microstructures to the sphere-like nanoparticles as the Li(OH) dosage increased. The photocatalytic results showed that all samples exhibited much higher photocatalytic activities than that of pure Bi 2 O 3 and TiO 2 (P25) in photocatalytic degradation of methyl blue (MB) under visible-light irradiation. Whereas BTL4 sample exhibited the highest photoactivity with increasing the dosage of Li(OH) to 2   mmol. Furthermore, the absorption edge of the Bi 2 O 3 /TiO 2 series composites displayed a broad-spectrum photoabsorption from UV to visible-light compared with the individual component. The as-synthesized Bi 2 O 3 /TiO 2 composites possessed excellent photocatalytic activity and outstanding recyclability. The enhanced photocatalytic efficiency was mainly attributed to the Bi 2 O 3 /TiO 2 p - n heterojunctions and hierarchical nanostructure. The recombination of photogenerated electron–hole pairs was efficiently suppressed by the Bi 2 O 3 /TiO 2 p - n heterojunctions.