Synthesis of NiTiO3–Bi2MoO6 core–shell fiber-shaped heterojunctions as efficient and easily recyclable photocatalysts†
Abstract
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 ∼8 nm and length of ∼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 (˙O2−) 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.