TiO2 cellular-protected nanowire array fabricated super-rapidly by the precipitation of colloids in the nanopores

Abstract

Recently, the highly isolated TiO₂ nanowire array has attracted much interest because of its advantages in a wide range of applications of this material, including dye sensitized solar cells and photocatalysis. The present work describes a high isolation of TiO₂ nanowires in the cellular protected nanowire (CPNW) array obtained by KOH–HCl alternative treatment of the as-anodized TiO₂ nanotube array at room temperature. The nanowires in the cells are highly separated from each other due to the successful suppression of the domino bundling effect by the cells. The mechanism of the CPNW formation is argued to be the dissolution–precipitation of TiO₂ nanoclusters. It is demonstrated that the nanopore-confined TiO₂ colloid, due to the different influence of drag force associated with the confined Brownian motion, will essentially precipitate in the center of the nanopore to form an isolated TiO₂ nanowire. Benefiting from the additional surface area and high isolation of TiO₂ nanowires in the CPNW array, the TiO₂ CPNW array has a better performance than the TiO₂ nanotube array in the application of DSSCs.