Solvothermal synthesis of BiOI microspheres: Effect of the reaction time on the morphology and photocatalytic activity

BiOI microspheres were synthesized by a solvothermal synthesis route from Bi(NO3)3·5H2O, using ethylene glycol in the presence of the ionic liquid 1-butyl-3-methylimidazolium iodide. The autoclave temperature was maintained constant at 120 °C and the reaction time was varied from 2 to 48 h. The obtained materials were characterized by XRD, SEM, TEM, EDS, nitrogen adsorption, FTIR and DRS. In addition, the photocatalytic activity of synthesized BiOI was evaluated in the oxidation of caffeic acid under simulated solar irradiation. Samples obtained between 12 and 24 h of synthesis present microsphere shapes and higher photocatalytic activity. All materials exhibit higher activities than TiO2 Evonik P25 used as standard catalyst.