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

Abstract

The present study describes the strategic doping of Fe metal ions into a BiOI microstructure using <i>ex situ</i> and <i>in situ</i> processes to synthesize a Fe-BiOI microstructure and their effect on photocatalytic degradation of tetracycline (TC). The data suggested that <i>in situ</i> Fe-BiOI (Fe-BiOI-In) has superior performance compared to <i>ex situ</i> 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 <i>in situ</i> 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.