Methylammonium iodo bismuthate perovskite (CH ₃ NH ₃ ) ₃ Bi ₂ I ₉ as new effective visible light-responsive photocatalyst for degradation of environment pollutants

In this work, the photocatalytic activity of a new visible light-responsive (CH ₃ NH ₃ ) ₃ Bi ₂ I ₉ hybrid organic-inorganic perovskite (HOIP) was addressed for the very first time in the treatment of aqueous solutions of model organic dyes. The photocatalyst was successfully prepared by a low temperature solvo-termal method, easily reproducible. The catalyst was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction spectrometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray photoelectron spectroscopy (XPS) techniques and UV diffuse reflectance spectrum. The efficiency of photocatalyst was tested for the removal of different type of dyes: fluorone dye (rhodamine B), thiazine dye (methylene blue) and azo dye (reactive Blue 4). Moreover, a multi-contaminated solution, with methylene blue and crystal violet (triarylmethane dye), was used to simulate a real industrial wastewater effluent. The results highlighted an increase of the photocatalytic activity respect the pristine precursor, bismuth iodide. The experiments showed that the values of removal was higher for rhodamine B respect the other dyes, with a removal of 98% after three hours under visible light irradiation. The efficiency of the photocatalyst was also confirmed under optimal conditions with high pressure liquid chromatography (HPLC). The gradual disappearance of rhodamine B peak accompanied by the appearance of by-products peaks was investigated. The stability of the photocatalyst was tested for three consecutive re-cycles. Analysis on different visible light sources was performed: halogen provided higher efficiency respect LED lamp. The outcomes of the present work aim to open the possibility of considering HOIP as a new potential photocatalyst for contaminants treatment.