Photocatalytic activity of BiOCl thin films deposited by thermal evaporation

Highlights: •BiOCl thin film was prepared by first time by thermal evaporation. •The evaporation process promotes a strong anisotropy of the BiOCl thin film. •BiOCl films have photocatalytic activity in aqueous media under UV–vis irradiation. •BiOCl films have photocatalytic activity under UV–vis irradiation in gaseous phase. -- Abstract: Thin films of BiOCl were prepared by a sequential evaporation process in a Thermal Evaporation System (TES) starting from BiOCl powders previously synthesized by co-precipitation. The films with 300 nm of thickness were deposited with a rate of 0.12 Ås⁻¹ to get a controlled evaporation of the material. BiOCl thin films deposited over microscope glass slides were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (HRTEM). The analysis by XRD confirmed the formation of BiOCl, showing a high degree of preferential crystalline orientation in {001} planes. In the same way, SEM analysis showed that the deposition of the oxyhalide took place by the formation of particles with shape of plates and small flowers. The photocatalytic activity of BiOCl thin films was evaluated in the degradation reaction of rhodamine B (RhB) in aqueous solution, and in the photocatalytic oxidation reaction of nitric oxide (NO) in gaseous phase. In both cases was confirmed the activity of the surface of the BiOCl films when it was activated by sun-like irradiation.