Structural, morphological, optical and photocatalytic characterization of ZnO–SnO2 thin films prepared by the sol–gel technique

Abstract

► Thin films of the mixed ZnO–SnO 2 system are obtained by the sol–gel technique. ► ZnO–SnO 2 system films show greater photocatalytic activity than SnO 2 and ZnO films. ► Highest photocatalytic activity is obtained for Zn:Sn(80:20) films. ► The photocatalytic reaction characterized in methylene blue is of first order. ► The highest k rate constant is 0.7 h −1 similar to TiO 2 nanostructured films. Thin films of the mixed ZnO–SnO 2 system were obtained by employing the sol–gel technique, starting from the mixture of zinc oxide and tin oxide precursor solutions. The tin atomic concentration percentages ( X ) in the precursor solutions with respect to the ZnO + SnO 2 total growing solution were: 0, 10, 20, 30, 40 and 100 at.%, here, the ZnO atomic percentage is (100– X ). The films were deposited by the dip coating method on glass substrates and were sintered at 450, 500 and 550 °C, in an open atmosphere. The X-ray diffraction patterns show the presence of zinc oxide and tin oxide crystals. The optical properties of the films were studied by UV–vis spectroscopy. The photocatalytic activity was quantified by means of the bleaching of methylene blue. The films of the mixed ZnO–SnO 2 system show higher photocatalytic activity than the SnO 2 and ZnO films.