Novel FeVO4/Bi7O9I3 nanocomposite with enhanced photocatalytic dye degradation and photoelectrochemical properties

Novel FeVO4/Bi7O9I3 nanocomposites with different weight percentages (3, 6.25, 12.5, and 25%wt) of FeVO4 were successfully synthesized by cyclic microwave irradiation, followed by wet impregnation. The applications for photocatalytic dye degradation and photoelectrochemical (PEC) were investigated. The 6.25%wt-FeVO4/Bi7O9I3 nanocomposite exhibited excellent photocatalytic degradation of methylene blue, rhodamine B, and methyl orange with decolorization efficiencies of 81.3%, 98.9%, and 94.9% within 360 min, respectively. Moreover, this nanocomposite possessed excellent reusability and stability during the photocatalytic degradation process. PEC performance in water oxidation of the 6.25%wt-FeVO4/Bi7O9I3 photoanode was evaluated by linear sweep voltammetry (LSV) measurement. Enhanced PEC performance with photocurrent density of 0.029 mA cm−2 at 1.23 V (vs. RHE) was observed under visible-light irradiation, which was ca. 3.7 times higher than that of the pure Bi7O9I3. Based on the optical characterization, energy band positions, and active species trapping experiments, a possible photocatalytic mechanism of the FeVO4/Bi7O9I3 heterojunction was discussed. The enhancement in the photocatalytic and the PEC performance ascribed to synergistic effects of visible-light absorption and a favorable “type II heterojunction” structure of the FeVO4/Bi7O9I3 nanocomposite. These were the main effects that promoted the photogenerated electrons and holes transfer across the contact interface between FeVO4 and Bi7O9I3, as well as suppressed the recombination of photogenerated electron-hole pairs and facilitated charge separation and transportation.