Different photo-catalytic degradation of methylene blue by varied ZnO nanorods on dissimilar stainless steel wire sieves

Methylene blue (MB) was degraded via ultraviolet (UV) irradiation by ZnO nanorods (ZnONRs) which were hydrothermally synthesized on stainless steel wire (SSW) sieves of different meshes. It was found that besides synthesizing parameters, the diameter of a SSW also affected the nucleation density of ZnO seeds and the size of diffuse zone of Zn²⁺ and O²¯ ions, and thus the surface morphology of the SSW-supported ZnONRs. The surface morphology of SSW-supported ZnONRs, together with the mesh size of a SSW sieve, further influenced significantly the wettability of the SSW sieve-supported ZnONRs. Of all three groups of SSW sieve-supported ZnONRs, those with Gaussian random rough surfaces are most hydrophilic, hence the actual contacting surface areas of (001) active crystal planes of ZnONRs with MB solution are the largest, the yield of hydroxyl radicals the highest, and eventually the photo-catalytic degradation of MB the optimal.