Superhydrophobic ZnO/TiO₂ heterostructure with significantly enhanced photocatalytic activity

ZnO/TiO₂ and TiO₂/ZnO thin films were prepared on borosilicate glass slide (BSG) by cost effective sol–gel spin coating technique. The films were characterized using X-ray diffraction, FESEM and FT-IR. The X-ray diffraction reveals the existence of both hexagonal ZnO and anatase TiO₂ phases for ZnO/TiO₂ and TiO₂/ZnO thin films. In the present work, an effort has been made to systematically study the wettability and photocatalytic activity of ZnO/TiO₂ and TiO₂/ZnO thin films. The wettability of the films was assessed by measuring the water contact angle (WCA). The WCA of ZnO/TiO₂ and TiO₂/ZnO was 43.6º and 26.3º respectively. The WCA of the films increases by modifying with octadecanoic acid (OA) where ZnO/TiO₂ shows superhydrophobic nature having WCA of 151.0º. The photocatalytic activities of the films were evaluated by measuring the degradation of methylene blue (MB) and octadecanoic acid under UV light. The photocatalytic efficiency of ZnO/TiO₂ was higher because of the formation of heterostructure which inhibits the charge recombination.