Novel Z-scheme MgFeO/BiWO heterojunction for efficient photocatalytic degradation of tetracycline hydrochloride: Mechanistic insight, degradation pathways and density functional theory calculations.

In this study, a new Z-scheme MgFeO/BiWO heterojunction was successfully prepared by hydrothermal and wet ball milling process. The results of the study showed that after 90 min of visible light exposure, the photocatalytic degradation of tetracycline hydrochloride (TCH) by 25%-MgFeO/BiWO heterojunction was as high as 95.82%, and the highest photocatalytic rate (0.0281 min) was 4.61 and 3.43 times higher than that of pure BiWO (0.0061 min) and MgFeO (0.0082 min), respectively. Furthermore, spin-polarized density functional theory (DFT) calculations were performed to provide additional evidence of the presence of a Z-scheme charge transfer mechanism between MgFeO and BiWO. We investigated the effects of initial TCH concentration, pH, coexisting ions and different water sources on the efficiency of photocatalytic degradation of TCH in composite samples. The recovery experiments demonstrated that the MgFeO/BiWO composites had good stability and repeatability. A series of experimental results showed that 25%-MgFeO/BiWO had a larger specific surface area, better ultraviolet and visible absorbance, superior charge transfer and higher efficiency of photogenerated electron-hole pair separation. This paper provides new ideas for the design and preparation of new Z-scheme heterojunctions and has great prospects for practical applications in the field of wastewater treatment.