Novel Fe-doped BiOI nanosheets attaching surface Fe (III) clusters: Additional superoxide radical and enhanced charge separation efficiency for remarkable tetracycline decomposition

Abstract

BiOI is a promising candidate for photocatalysis under visible-light irradiation, but its band characteristics is unfavorable for the generation of reactive oxygen species (ROS) and charge separation. Herein, a novel Fe-doped BiOI nanosheet with surface attached Fe (Ⅲ) clusters was fabricated via a facile hydrothermal method. Scanning electron microscopy images suggested that the introduction of mannitol and Fe-doping has a significant impact on the thickness and pore structure of BiOI nanosheets, and the specific surface area of which can reach to 70.58 m2/g. When the Fe/ Bi molar ratio was 8:100, the conduction band of the prepared BiOI presented a distinct upshift (from −0.28 eV to −1.41 eV), which is beneficial for producing more·O2-. The trapping experiments and electron spin resonance (ESR) results also proved that the·O2- was the main reactive specie for tetracycline decomposition. Besides, the photoluminescence (PL) spectra and electrochemical characterization results were combined to illustrate that the interfacial charge transfer (IFCT) induced by Fe (Ⅲ) clusters effectively inhibited the carriers recombination. As photodegradation experiment results showed, compared to the pure BiOI, the degradation efficiency of sample 8Fe-BiOI to tetracycline exhibited an enormous promotion (from 56.7 % to 100 %) at 90 min by 350 W Xe lamp irradiation. After five consecutive cycles, the degradation efficiency of the sample for tetracycline remained about 89 % of the initial value.