Synthesis of NiTiO3-Bi2MoO6 core-shell fiber-shaped heterojunctions as efficient and easily recyclable photocatalysts

Development of efficient and recyclable photocatalysts has drawn more and more attention. Herein, we have prepared a kind of core-shell fiber-shaped NiTiO3-Bi2MoO6 heterojunction as an efficient and easily recyclable visible-light-driven photocatalyst. NiTiO3 nanofibers have been obtained by an electrospinning-calcination method; and in situ growth of Bi2MoO6 is conducted on the surface of NiTiO3 by a simple solvothermal method. NiTiO3-Bi2MoO6 heterojunctions are composed of NiTiO3 nanofibers with a diameter of about 150 nm whose surfaces are decorated by Bi2MoO6 nanoneedles with a diameter of similar to 8 nm and length of similar to 35 nm. Under visible light irradiation, NiTiO3-Bi2MoO6 heterojunctions exhibit significantly high photocatalytic activities compared with NiTiO3, Bi2MoO6 and a mechanical mixture (22 wt% NiTiO3 + 78 wt% Bi2MoO6) when rhodamine B (RhB) or 4-chlorophenol (4-CP) are selected as model pollutants. For example, NiTiO3-Bi2MoO6 heterojunctions achieve the highest photodegradation efficiency of RhB (97.2%) compared to 21.9% by NiTiO3, 40.3% by Bi2MoO6 and 45.0% by the mechanical mixture. The enhanced photocatalytic activities can be mainly attributed to the efficient separation of photogenerated electron-hole pairs. During the photocatalytic degradation of RhB, superoxide radical ions (center dot O-2(-)) and photogenerated holes (h(+)) are detected as the main active species. Moreover, NiTiO3-Bi2MoO6 heterojunctions can be recycled by sedimentation and still possess excellent stability. Therefore, NiTiO3-Bi2MoO6 heterojunctions have great potential to act as efficient and recyclable photocatalysts in practical applications of environmental purification.