Photocatalytic degradation of RhB in wastewater by zinc ion-doped Bi5O7I

Bi5O7I doped with Zn2+ (Zn2+/Bi5O7I) was prepared using a precipitation calcination method. Its photocatalytic activity was improved by adjusting the band gap of Bi5O7I, and its photocatalytic performance was evaluated by degrading RhB. The experimental results showed that Zn2+/Bi5O7I-8 had the highest photodegradation efficiency, and the degradation rate for RhB after exposure to light for 30 minutes was 91% and reached 100% in 60 minutes. The degradation rate constant k of Zn2+/Bi5O7I-8 reached 0.10813 min−1, which is 13 times more than that of Bi5O7I. As a result of Zn2+ being added into Bi5O7I, the band gap of Zn2+/Bi5O7I became narrower than that of Bi5O7I, and the photogenerated electrons and holes were successfully prevented from recombining; therefore, the photocatalytic activity of Zn2+/Bi5O7I was higher than that of Bi5O7I. After four rounds of photocatalytic experiments, the photocatalytic efficiency of Zn2+/Bi5O7I-8 remained high. The composition and microstructure of the materials were characterized using XRD, FTIR, XPS, SEM, and TEM. The optical properties and degradation mechanism of the material were investigated using DRS, PL, photocurrent response, and active substance capture experiments. A suggested mechanism for the photocatalytic degradation of RhB is presented.