Ti O2 is an attractive material for photocatalytic water splitting, but its band gap is too large to allow for efficient absorption of solar photons. We present a comprehensive first-principles investigation of band-structure modifications induced by alloying Ti O2 with Ti S2. The band gap of Ti O2 (1-x) S2x alloys exhibits a dramatic decrease upon addition of even a low concentration of S. The optical absorption of visible light is attainable with sulfur concentrations less than x=0.25. We have verified that the band alignment in these alloys is favorable for photocatalytic applications: in particular, the conduction band exhibits only small shifts, while the majority of the band-gap change is due to an upward shift of the valence band.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)