Design of Narrow-Gap TiO2: A Passivated Codoping Approach for Enhanced Photoelectrochemical Activity

To improve the photoelectrochemical activity of TiO2 for hydrogen production through water splitting, the band edges of TiO2 should be tailored to match with visible light absorption and the hydrogen or oxygen production levels. By analyzing the band structure of TiO2 and the chemical potentials of the dopants, we propose that the band edges of TiO2 can be modified by passivated codopants such as (Mo+C) to shift the valence band edge up significantly, while leaving the conduction band edge almost unchanged, thus satisfying the stringent requirements. The design principle for the band-edge modification should be applicable to other wide-band-gap semiconductors.

National Basic Research Program of China G2009CB929300 National Natural Science Foundation of China 60521001 6077061U. S. DOE DE-AC36-08GO28308 J.L. gratefully acknowledges financial support from "One-hundred Talent Plan'' of the Chinese Academy of Sciences. This work is supported by the National Basic Research Program of China (973 Program) Grant No. G2009CB929300 and the National Natural Science Foundation of China under Grants No. 60521001 and No. 6077061. The work at NREL is supported by the U. S. DOE under Contract No. DE-AC36-08GO28308.