Heterostructured Bi2S3@NH2-MIL-125(Ti) nanocomposite as a bifunctional photocatalyst for Cr(vi) reduction and rhodamine B degradation under visible light

Abstract

A series of bismuth sulfide (Bi₂S₃) nanorods and amine-functionalized Ti-based metal–organic framework heterojunctions [denoted by Bi₂S₃@NH₂-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 NH₂-MIL-125(Ti) and Bi₂S₃, the as-synthesized Bi₂S₃@NH₂-MIL-125(Ti) photocatalyst exhibited an enhanced photocatalytic activity toward Cr(VI) and RhB owning to the synergetic effect between Bi₂S₃ and NH₂-MIL-125(Ti). Moreover, the Bi₂S₃@NH₂-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 Bi₂S₃ into NH₂-MIL-125(Ti) can extend the light adsorption and improve the transfer and separation of photogenerated charge carriers through the Bi₂S₃@NH₂-MIL-125(Ti) heterojunction with unique band gap structure. The synthesized Bi₂S₃@NH₂-MIL-125(Ti) photocatalyst also exhibited good reusability and stability.