Facile preparation of honeycomb-structured TiO2 nanofilm via breath figures assembly and coffee ring effect

Honeycomb-like porous TiO2 nanofilm was facilely prepared by a two-step self-assembly method. Firstly, a breath figure process was conducted to form an ordered composite film with micro-sized titanium salt particles in the polymer honeycomb holes. Secondly, the inorganic particles disintegrated into nano-sized particles and dispersed in water when a water drop was placed on the surface. The evaporation of water led to the formation of a “coffee ring”, with a very thin layer of TiO2 precursor on the polymer film. A honeycomb-structured TiO2 nanofilm was obtained after calcination.