Enhanced sunlight photo-catalytic performances of ZnO/ZnNb2O6/Nb2O5 composites for organic pollutant degradation
Abstrakt
The current study is focused on the development of zinc oxide-based ternary photo-catalysts that exhibit a good photocatalytic activity in methylene blue (MB) dye degradation, under sunlight irradiation. Indeed, the com-posites are prepared according to this proportion:(1-x) ZnO/xNb2O5, (x = 0; 0.01; 0.05; 0.1; 0.15; 0.2).
In fact, X-ray diffraction patterns demonstrate that, for x = 0.01, a binary composite ZnO/ZnNb2O6 is formed. While ternary composite ZnO/ZnNb2O6/Nb2O5 is formed from x = 0.05.
The linear and nonlinear optical properties are studied. So, compared to the ZnO (3.24 eV), the prepared composites exhibit a gap energy red-shift (3.18-3.22 eV), probably due to the interactions between oxide phases.
Furthermore, the composites exhibit a high optical conductivity, which proves their high photo-responses. On the other hand, the increase of Nb2O5 amount led to an enhancement of nonlinear properties.
Moreover, the photocatalytic tests demonstrate an excellent photo -catalytic performance in MB degradation that reaches 100% after 120 min sun-light irradiation. Especially for 5% sample which exhibit also the best kinetic rate.
These results allowed us to consider the ZnO/ZnNb2O6/Nb2O5 composites as promising materials for environmental applications.