Size- and density-controlled synthesis of TiO2 nanodots on a substrate by phase-separation-induced self-assembly

This work presents a facile way, i.e. phase-separation-induced self-assembly, to prepare TiO2 nanodots on a substrate. This method induces convective flow in a spin-coated titanium tetrabutoxide (TBOT)/polyvinyl pyrrolidone (PVP)/ethanol liquid film through the Marangoni effect and turns TBOT into crystalline TiO2 nanodots on a substrate after calcination. The size and density of the TiO2 nanodots can be finely tailored by controlling the concentrations of TBOT and PVP in the precursor sol. The TiO2 nanodot-deposited surface showed a hydrophilic characteristic and the wettability was obviously improved by increasing nanodot size.