The p-n heterojunction with porous BiVO4 framework and well-distributed Co3O4 as a super visible-light-driven photocatalyst

The p-n heterojunction with mesoporous BiVO4 framework well-distributed Co3O4 is fabricated. The mesoporous structure is prepared by nanocasting technique using KIT-6 as template, while the incorporation of Co3O4 particles is completed by the impregnation technique. Transmission electron microscopy (TEM) image shows that Co3O4 particles have been successfully loaded in the framework of the mesoporous BiVO4. Energy dispersive spectrum (EDS) mapping reveals that Co3O4 particles distribute uniformly in the sample, which is the result of the template effect of the mesoporous structure. The photocatalytic removal rate of RhB with BiVO4 is enhanced by the construction of the pn heterojunction of Co3O4/mesoporous BiVO4. This increase can be attributed to the enhanced separation efficiency of the photogenerated charge carriers produced by the p-n heterojunction. Mesoporous BiVO4 enables the guest material of Co3O4 to be well distributed in the matrix of the mesoporous BiVO4, thereby providing a large contact area of Co3O4 and BiVO4. This promotes the charge transferring across the interface, thereby increasing the separation of electron-hole pairs, and leading to the enhancement of photocatalytic ability. Furthermore, the mesoporous structure itself contributes to the enhanced photocatalytic performance.