Synthesis, characterization, and visible-light photocatalytic activity of BiOI hierarchical flower-like microspheres

Abstract

BiOI hierarchical flower-like microspheres were hydrothermally prepared, using tetrabutylammonium iodide as an iodine source and template. Many BiOI hierarchical structures have been synthesized using KI, NaI, HI or ionic liquids as the iodine source, but the use of alkyl ammonium iodide as the iodine source was not reported in the literature. The so-obtained BiOI samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen sorption measurements, and ultraviolet-visible diffuse reflectance spectroscopy. The effects of hydrothermal temperature and time on the BiOI crystal structure and morphology were investigated. The BiOI microspheres were composed of BiOI nanosheets. The photocatalytic performance of the BiOI samples was determined from the degradation of Rhodamine B, under visible light irradiation. BiOI microspheres prepared at 160 °C over 30 h exhibited excellent photodegradation efficiency, which was more than five and seven times higher than those of BiOI nanoplates and N-doped TiO₂, respectively. The high photocatalytic performance was attributed to the high specific surface area and low nanosheet thickness. A morphologic factor was proposed to represent the ratio of specific surface area to nanosheet thickness, and correlated to the photodegradation efficiency of the BiOI samples. The photocatalytic efficiency increased with increasing morphologic factor. The BiOI photocatalyst exhibited excellent stability and reusability, and has potential in environment remediation.