Construction of the Bi2WO6/Bi4V2O11 heterojunction for highly efficient visible-light-driven photocatalytic reduction of Cr(vi)

Abstract

Herein, a Bi₂WO₆/Bi₄V₂O₁₁ heterostructured photocatalyst was fabricated through a facile one-pot solvothermal method. In this heterojunction system, highly homogeneous-dispersed Bi₄V₂O₁₁ nanocrystals were anchored onto Bi₂WO₆ nanoflakes, endowing the heterojunction with nanosized interfacial contact. Because of the favorable interfacial contact and band alignment, photoinduced charge carrier transfer is facilitated in the Bi₂WO₆/Bi₄V₂O₁₁ heterojunction, which can be verified by photocurrent and photoluminescence measurements. In contrast with pristine Bi₂WO₆ and Bi₄V₂O₁₁ samples, the Bi₂WO₆/Bi₄V₂O₁₁ heterostructured photocatalyst displays drastically improved photocatalytic Cr(VI) reduction activity under visible-light irradiation. More significantly, the as-fabricated heterojunction possesses superior activity for Cr(VI) relative to the counterpart obtained by mechanical mixing, indicating that the interfacial contact plays a determinant role in promoting charge carrier transfer. Moreover, Bi₂WO₆/Bi₄V₂O₁₁ heterojunctions exhibited good cycling stability even after 5 cycles. A plausible photocatalytic Cr(VI) reduction reaction mechanism over the Bi₂WO₆/Bi₄V₂O₁₁ heterojunction is proposed on the basis of band alignment. This work reports a high-efficiency photocatalyst for Cr(VI) and might shed light on the decisive factor for optimizing the heterostructure.