Photocatalytic degradation of methylene blue using a ZnO/TiO2 heterojunction nanomesh electrode

In the present research, ZnO/TiO2 heterojunction nanomeshes (HNMs) were synthesized by anodizing and calcination. The structural study revealed the as-synthesized samples were composed of anatase TiO2, rutile TiO2,and zincblende-structured ZnO. TiO2 segments had a preferred orientation along the [110] direction, whereas ZnO nanoparticles were oriented along the [200] direction. In comparison to pure TiO2 nanomeshes, ZnO/TiO2 HNMs had higher methylene blue (MB) photodegradation capacity. Furthermore, the effects of different parameters, such as calcination temperature, initial pH, and mesh density, on MB photodegradation were investigated. The superior photocatalytic activity was achieved by the sample calcinated at 600°C due to the appearance of zinc-blende ZnO and the mixed crystal phases of anatase and rutile TiO2. A high degradation efficiency was obtained under alkaline conditions. When the mesh density was 200 per inch, the maximum photodegradation efficiency was achieved.