Diversityof TiO2: Controlling the Molecularand Electronic Structure of Atomic-Layer-Deposited Black TiO2

摘要

Visually black, electrically leaky, amorphous titania (am-TiO2) 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 Ti³⁺ in the film. Oxidation of Ti³⁺ upon heat treatment leads to a drop in conductivity, a color change from black to white, and crystallization of am-TiO2. ALD-grown black TiO2, 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 TiO2.