A Hierarchically Ordered TiO 2 Hemispherical Particle Array with Hexagonal‐Non‐Close‐Packed Tops: Synthesis and Stable Superhydrophilicity Without UV Irradiation

A hierarchical TiO 2 ordered hemispherical particle array with hexagonal‐non‐close‐packed (hncp) tops is prepared by pulsed laser deposition (PLD) using a polystyrene colloidal monolayer as a template. Compared with conventional lithography, the route presented has the advantage of low cost for producing hncp nanostructured arrays. This hierarchical particle array exhibits excellent superhydrophilicity with a water contact angle of 0° without further UV irradiation. The superhydrophilic property originates from oxygen defects or vacancies on the surface of the TiO 2 nanoparticles produced by PLD and the increased roughness of the hierarchical particle arrays. More importantly, this property is very stable for half a year and could be used in self‐cleaning surfaces and microfluidic devices.