Diversity of TiO(2): Controlling the Molecular and Electronic Structure of Atomic-Layer-Deposited Black TiO(2)

[Image: see text] Visually black, electrically leaky, amorphous titania (am-TiO(2)) thin films were grown by atomic layer deposition (ALD) for photocatalytic applications. Broad spectral absorbance in the visible range and exceptional conductivity are attributed to trapped Ti(3+) in the film. Oxidation of Ti(3+) upon heat treatment leads to a drop in conductivity, a color change from black to white, and crystallization of am-TiO(2). ALD-grown black TiO(2), without any heat treatment, is subject to dissolution in alkaline photoelectrochemical conditions. The best photocatalytic activity for solar water splitting is obtained for completely crystalline white TiO(2).