The role of the molar ratio of (HNO3/Bi3+) on the formation and morphology of α-Bi2O3 microrods with photocatalytic properties

Enlarged microrods α-Bi2O3 were directly obtained by chemical precipitation method at soft reflux conditions using ethylenediamine-solvent as precipitating and morphological template, in absence or presence of nitric acid. The influence of the molar ratio of HNO3/Bi3+ (0, 5 and 10) and reflux temperature, maintaining fixed the Bi3+ content in solution, on the formation of Bi2O3 or amorphous-compounds was investigated. The structure and properties of the α-Bi2O3 obtained by the direct precipitation condition or after calcination were obtained by X-ray diffraction, infrared analysis, diffuse reflectance spectroscopy and scanning electron microscopy. A relationship between the reflux temperature and the molar ratio of HNO3/Bi3+ ions for the direct formation of α-Bi2O3 phase is discussed. The photocatalytic properties, recyclability and stability of α-Bi2O3 solids were tested in the photodegradation of indigo carmine dye under UV-Light. X-ray diffraction and infrared analysis of the re-used α-Bi2O3 were also included.