High Photocatalytic Activity of the TiO2/ZnO Mesoporous Composites Obtained by Solution Combustion Method

In this work, the high photocatalytic activity of the TiO2/ZnO mesoporous composites for the
degradation of Methylene Blue and Rhodamine B dyes is reported. The composites were obtained by
the solution combustion method at different ZnO/TiO2 ratios in short synthesis times. X-Ray diffraction
shows TiO2 in the anatase phase and a hexagonal wurtzite structure for ZnO. According to these
results, when the incorporation of ZnO into TiO2 exceeds 32%, the zinc excess promotes the
formation of zinc titanate. The UV-vis spectra for the composite show an absorption in the visible
region associated with oxygen vacancies and carbon incorporated into to the ZnO during the
combustion process. The EDS analysis shows a carbon incorporation of up to 3.47%. When the
photocatalytic process is carried out with UV-vis radiation, the photocatalytic activity improved by up
to 20% compared to that obtained when used UV radiation only. The highest photocatalytic activity is
presented by the semiconductor composite whose ZnO content is 32.1%. The improvement in
photocatalytic activity is associated with a larger surface area and a better pore size distribution.