Photochemical Activity of Nitrogen-Doped Rutile TiO₂(110) in Visible Light

Abstract

TiO2(110) single crystals, doped with nitrogen via an NH3 treatment at 870 K, have been found to exhibit photoactivity at photon energies down to 2.4 eV, which is 0.6 eV below the band-gap energy for rutile TiO2. The active dopant state of the interstitial nitrogen that is responsible for this effect exhibits an N (1s) binding energy of 399.6 eV and is due to a form of nitrogen that is probably bound to hydrogen, which differs from the substitutional nitride state with an N (1s) binding energy of 396.7 eV. Optical absorption measurements also show enhanced absorption down to 2.4 eV for the NH3-treated TiO2(110). A co-doping effect between nitrogen and hydrogen is postulated to be responsible for the enhanced photoactivity of nitrogen-doped TiO2 materials in the range of visible light.

Improved photovoltaic performance of dye-sensitized solar cells with modified self-assembling highly ordered mesoporous TiO2 photoanodes

“…Highly-transparent and highly-ordered TiO 2 mesoporous multilayer thin films with variable thicknesses were fabricated via 30 an evaporation induced self-assembly method. The conversion efficiency of the highly-ordered TiO 2 thin film solar cells (0.82%) was 5 times superior to that of the transparent Solaronix photoanode solar cells (0.16%), with photoanodes of a similar thickness (approximately 1 µm).…”

“…28 This result has been accepted by other researchers. [29][30] As for the peak at 398 27 However, Zhou et al suggested that the 398 eV peak should be attributed to the invasion of N atoms into the interstitial sites of the TiO 2 crystal lattice , expressed as the Ti-N-O bond, and this conclusion was confirmed by a 55 temperature programmed desorption (TPD) experiment. 31 In our study, the absence of any peak around 400 eV in the N 1s spectrum implies that there were no adsorbed nitrogen molecules in our samples.…”

“…The adsorbed dye-molecules are capable of absorbing light and injecting electrons into the TiO 2 conduction band. The electrons are then collected at a back conducting electrode, 30 generating a photocurrent. Therefore, one of the key issues for superior DSSCs is the morphological engineering of the TiO 2 photoanode.…”

Comment on “Enhancement of room temperature ferromagnetism in N-doped TiO2−x rutile: Correlation with the local electronic properties” [Appl. Phys. Lett. 97, 012506 (2010)]

“…This assignment can also be proved by the previous literature. 2,3 The BE of N 1s is even lower than that of titanium nitride, suggesting more charge transfer to the N ions and further oxidizing the Ti ions ͑e.g., from Ti 3+ to Ti 4+ ͒. This will break the charge balance in the TiO 2 system.…”

Electronic and optical properties of Ti1−xCdxO2: A first-principles prediction

“…The band gap is about 2.21 eV at highly symmetric G point, which is less than the experimental value of 3.0 eV. 19 The underestimated band gap can be due to the choice of exchange-correlation energy. The valence band mainly consists of the 2p, 2s states of O and 3d states of Ti.…”