Fabrication of black hierarchical TiO2 nanostructures with enhanced photocatalytic activity

Abstract

Here, we report the fabrication of hierarchical TiO₂ nanostructures with wire-in-tube architectures by hydrothermal treatment of anodic TiO₂ nanotubes. The mechanism for this morphological evolution was understood by dissolution-precipitation of TiO₆²⁻ octahedra. Sintering the hierarchical TiO₂ nanostructures under vacuum condition created black TiO₂ nanostructures, which show anatase phase with self-doped Ti³⁺ present in the bulk. Due to the reduced band gap, increased donor density, and enlarged active interface, the black hierarchical TiO₂ nanostructures demonstrated efficient photocatalytic performance under both full spectrum and visible light illumination.