Hierarchical TiO₂ nanoparticle arrays with hexagonal-non-close-packed arrangement and their stable superhydrophilicity without UV irradiation

Abstract

Here we present a new route to fabricate hexagonal-non-close-packed (hncp), hierarchical TiO2 ordered nanoparticle array film by pulsed laser deposition (PLD) using polystyrene (PS) colloidal monolayer as a template. TiO2 was deposited onto the monolayer PS colloidal crystal template by PLD using rutile TiO2 pellet as a target and oxygen as the background gas. After annealing at 650 C for 2 h in air, the hncp, anatase typed hierarchical TiO2 nanoparticle array was obtained. Each large nanoparticle in the ordered array was composed of smaller nanoparticles (30 nm). This hierarchical nanoparticle array exhibits strong superhydrophilicity with water contact angle of 0 degree without further UV irradiation.