Large-scale fabrication of ordered nanobowl arrays

A novel approach is presented for the large-scale fabrication of ordered TiO2 nanobowl arrays. The process starts with a self-assembled monolayer of polystyrene spheres, which is used as a template for atomic layer deposition of a TiO2 layer. After ion-milling, toluene-etching, and annealing of the TiO2-coated spheres, ordered arrays of nanostructured TiO2 nanobowls have been fabricated. The nanobowls exhibit smooth interior and exterior surfaces and uniform sizes and thickness. The nanobowl arrays have been demonstrated to be useful for selecting spheres smaller than the inner diameter of the bowls. This approach can be extended to a wide range of coating materials and substrates (ceramics, metals, polymers, glasses) with controlled wall thickness and size.