Facile synthesis of MnWO4/BiOI nanocomposites and their efficient photocatalytic and photoelectrochemical activities under the visible-light irradiation

The novel MnWO4/BiOI nanocomposite materials were successfully synthesized by a precipitation deposition method. The as-prepared photocatalyst was characterized by XRD, SEM, EDAX, UV-DRS, FT-IR, TEM and BET techniques. The as-prepared MnWO4/BiOI nanocomposites were further utilized to study the degradation of the Celestin blue aqueous solution under visible-light irradiation. Absorption range and band gap energy, which are responsible for the observed photocatalyst behavior, were investigated by the DRS spectroscopy. The photocatalytic test suggested that MnWO4/BiOI nanocomposites possess a higher activity for the degradation of these pollutants than the pure BiOI and MnWO4 under the visible-light irradiation. Among the as-prepared nanocomposites, the one of 3% MnWO4/BiOI displays the best photocatalytic activity of the degradation. Factors, such as the effect of the catalyst dosage, the solution pH and the initial dye concentration affecting the photocatalytic activity were investigated. The investigations of the adsorption kinetics and isotherm demonstrate that the adsorption process follows the pseudo-first-order kinetic model and the Langmuir adsorption isotherm, respectively.