Shell thickness dependent photocatalytic activity of TiO₂/ZnS core-shell nanorod arrays

Rutile TiO₂ nanorod arrays (NRAs) were first fabricated via solvothermal route using Ti foil as both substrate and titanium source, then TiO₂/ZnS core-shell heterostructure NRAs were synthesized by successive ionic layer adsorption and reaction (SILAR) method using the TiO₂ NRAs as a sacrificial template. The diameters of TiO₂ nanorods ranged from 20 to 200 nm, and the thickness of ZnS shell varied from 3 to 20 nm. The photocatalytic activities of the samples were compared by the degradation of rhodamine B (RhB) water solution under simulated sunlight irradiation. All TiO₂/ZnS NRAs exhibited higher photocatalytic activities than bare TiO₂ NRAs, and the optimal ZnS shell thickness of TiO₂/ZnS NRAs was 10 nm. Furthermore, TiO₂/ZnS NRAs possessed excellent reusability. (paper)