Effect of the KOH chemical treatment on the optical and photocatalytic properties of BiVO4 thin films
Résumé
In this work, we present the structural, optical and photocatalytic properties of BiVO4 thin films produced by a dual-magnetron sputtering process using both Bi2O3 (alpha-phase, 99.98 % purity) and V (99.9 % purity) targets under Ar/O-2 atmosphere with a ratio of 18:2. The films were deposited varying the power applied to the targets to obtain stoichiometric films, and the monoclinic structure was achieved by post-deposition annealing. The dual process was chosen to better control the Bi/V ratio since Bi and V have very different sputtering yields. In particular, the influence of a chemical treatment using potassium hydroxide (KOH) on the optical properties and different dye discolorations (acid blue 113 and methyl orange) is discussed. The optical properties were studied by reflectance and transmittance spectroscopy, where the spectra were fitted to obtain the refractive index dispersion and the optical band gap of the BiVO4 as a function of the film structure, as determined by X-ray diffraction and Raman spectroscopy.