Photocatalytic properties of the g-C3N4/{010} facets BiVO4 interface Z-Scheme photocatalysts induced by BiVO4 surface heterojunction

摘要

The g-C3N4/{010} facets BiVO4 interface Z-scheme photocatalysts is fabricated by ultrasonic dispersion method. The density functional theory (DFT) shows that the differences of the energy levels in the conduction bands and the valence bands between the {010} and {110} facets of BiVO4 is about 0.37 and 0.31 V (vs. NHE, pH = 7), respectively. Therefore, the co-exposed {010} and {110} facets of BiVO4 can form surface heterojunction, which promotes the {010} facets of BiVO4 with negative charge. The zeta potential indicates that layered g-C3N4 with positive charge. The Raman, FT-IR and XPS analysis demonstrates that the layered g-C3N4 is anchored on the {010} facets of BiVO4 through strong interface electrostatic interaction, which leads to form a built in electric field at the contact interface. Under the built-in electric field driving, photogenerated electrons in the CB of {010} facets of BiVO4 rapidly recombines with the holes in the VB of g-g-C3N4 to form the interface Z-scheme heterostructure. That is, BiVO4 surface heterojunction ultimately induces the formation of interface Z-scheme heterostructure. The interface Z-scheme heterostructure not only facilitates the space separation of the photogenerated carriers, but also accumulates electrons in the more negative potentiated CB of g-C3N4 and holes in the more positive VB of {110} facets of BiVO4. Consequently, by means of the I-t, ISV and EIS measurements, the g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts presents extraordinary photoelectrochemical performance. More importantly, the degradation rate of g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts can reach the highest 88.3% within 30 min under visible light irradiation, and the mineralization ability (96.03%) is about 2.24 and 3.32 times as high as that of BiVO4 (42.83%) and g-C3N4 (28.89%), respectively.