Wide band gap TiO2 has strong oxidation potential attributed to its very positive value of the top of the valence band. Which narrow band gap oxide semiconductor has more positive valence band potential than TiO2?
See Figure 27 in Robertson's famous review on high-k dielectrics
http://iopscience.iop.org/0034-4885/69/2/R02
It doesn't contain TiO2, but if you look at Table 2 you can find TiO2 versus Si and from there you can draw it on Fig. 27. Note that some of these values are from theoretical calculations and are not always the most accurate, but they are a good starting point. Furthermore, you can engineer the bands between TiO2 and the other material by creating interfacial dipoles
Dear Andris
The valence band maximum of TiO2 is located at about 7.8 eV and its band gap is about 3.3 eV. If you are looking for a metal oxide with narrower band gap and shallower valence band edge you have to try one of the follwing oxides: CuO, Cu2O3, CoO, Co3O4, NiO, MoO2, Cr2O3. All those oxides exhibit smaller band gap than TiO2 and have their VB edge in the range of 5.5-6.5 eV.
Dear Andris,
The photovoltaic chemistry isn't my research direction, but as far as I know the gallium oxide now is promising material.
DOI: 10.1039/C4TA03193H
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