Fabrication of TiO2 and Ag wires and arrays using opal polystyrene crystal templates

Monodispersed polystyrene (PS) colloids suspended in an aqueous phase with diameters of 46±2.0 and 903±9nm were employed to deposit opal templates on electrically conductive diamond substrates using a drop-dry method. Ordered close-packed polystyrene opals were produced in the case of the larger PS spheres. In contrast the smaller spheres exhibited a more disordered packing and produced a periodic arrangement of linear voids as a result of the capillary forces operating during the drying process. The PS arrays produced in this way were infiltrated with titania colloidal solution (particle size of 230nm), followed by drying, dissolution of the PS and calcination. This produced inverse opal titania in the anatase phase for the 903nm PS spheres, whereas it is shown that the structure using the smaller PS spheres is dominated by microwire arrays as a result of the linear voids present in the original template. It is shown that electrochemically deposited Ag also adopts a similar microstructure when using this template.