Strategic Doping Approach of the Fe–BiOI Microstructure: An Improved Photodegradation Efficiency of Tetracycline

[Image: see text] The present study describes the strategic doping of Fe metal ions into a BiOI microstructure using ex situ and in situ processes to synthesize a Fe–BiOI microstructure and their effect on photocatalytic degradation of tetracycline (TC). The data suggested that in situ Fe–BiOI (Fe–BiOI-In) has superior performance compared to ex situ Fe–BiOI (Fe–BiOI-Ex) due to the uniform dispersion of Fe within the Fe–BiOI material. Calculated bandgaps ∼1.8, ∼1.5, and 2.4 eV were observed for BiOI (without Fe), Fe–BiOI-In, and Fe–BiOI-Ex, respectively. Interestingly, Fe incorporation within BiOI might decrease the bandgap in Fe–BiOI-In due to the uniform distribution of metal ions, whereas increasing the bandgap in Fe–BiOI-Ex attributed to nonuniform distribution or agglomeration of metal ions. The uniform dispersion of Fe within Fe–BiOI modulates electronic properties as well as increases the exposure of Fe ions with TC, thereby higher degradation efficiency of TC. The in situ Fe–BiOI material shows 67 and 100% degradation of TC at 10 and 1 mg/L, respectively. The TC degradation was also found to be pH-dependent; when increasing the pH value up to 10, 94% degradation was achieved at 10 mg/L within 60 min of solar irradiation. The analysis was also performed over BiOI, which proves that Fe has a profound effect on TC degradation as Fe(II) tends to trigger oxidation–reduction by utilizing the chelate formation tendency of TC. Therefore, the prepared Fe–BiOI-In has the potential ability to degrade pharmaceutical compounds, especially, TC from wastewater.