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

Abstract

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.