Heterostructured Bi 2 S 3 @NH 2 -MIL-125(Ti) nanocomposite as a bifunctional photocatalyst for Cr(vi) reduction and rhodamine B degradation under visible light.

A series of bismuth sulfide (Bi 2 S 3 ) nanorods and amine-functionalized Ti-based metal-organic framework heterojunctions [denoted by Bi 2 S 3 @NH 2 -MIL-125(Ti)] were constructed and explored as bifunctional photocatalysts for Cr(vi) reduction and rhodamine B (RhB) degradation under visible light illumination. Compared with the individual NH 2 -MIL-125(Ti) and Bi 2 S 3 , the as-synthesized Bi 2 S 3 @NH 2 -MIL-125(Ti) photocatalyst exhibited an enhanced photocatalytic activity toward Cr(vi) and RhB owning to the synergetic effect between Bi 2 S 3 and NH 2 -MIL-125(Ti). Moreover, the Bi 2 S 3 @NH 2 -MIL-125(Ti) heterojunctions showed increased Cr(vi) removal efficiency by adding RhB in the system. The photocatalytic mechanism was proposed based on the analysis of different scavenger for active species and electron spin resonance spectrometry. The introduction of Bi 2 S 3 into NH 2 -MIL-125(Ti) can extend the light adsorption and improve the transfer and separation of photogenerated charge carriers through the Bi 2 S 3 @NH 2 -MIL-125(Ti) heterojunction with unique band gap structure. The synthesized Bi 2 S 3 @NH 2 -MIL-125(Ti) photocatalyst also exhibited good reusability and stability.