The calculations show that although the band gap in NbTi, 2NbTi, and NbTi+Oi systems is small, the intragap states would be the electron-hole recombination center, leading to low photocatalytic efficiency.On the basis of the charge-compenstated theory, two electrons on the transition-metal Nb atoms compensate for the same amount of holes on the acceptor level of a nonmetal intersitial O atom, in the model of 2NbTi+Oi. Such donor-acceptor codoping may not only suppress the electron-hole recombination but also maintain a reduced band gap, suggesting that the doping models would exhibit higher photocatalytic activity than pure TiO2. The calculation results show that the intersitital O atoms play an essential role in manipulating the valence state of impurity Nb. The role of the intersitial O atom in Nb-doped rutile TiO2 suggests that it can give rise to beneficial charge-compensation effects.

Niobium-doped TiO2: Effect of an interstitial oxygen atom on charge state of niobium

2019 Fall National Meeting

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