Photoelectrochemical and photocatalytic properties of N+S co-doped TiO2 nanotube array films under visible light irradiation

Abstract

a b s t r a c tIn this paper, we report on the co-doping nitrogen and sulfur has been achieved in the TiO 2 nanotube array films by treatment with thiourea and calcination under vacuum at 500• C for 3 h. The samples were characterized by scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy. XPS spectra revealed that N might coexist in the forms of N Ti O and N O Ti, S was incorporated into the lattice of TiO 2 through substituting oxygen atoms in the N + S co-doped TiO 2 nanotube array films. XRD patterns indicated that improved crystallinity was obtained for N + S co-doped TiO 2 nanotube arrays as compared to that of undoped TiO 2 nanotube arrays. In photoelectrochemical measurements, the photocurrent of N + S co-doped TiO 2 nanotube array films was greatly enhanced compared to that of undoped samples under visible light irradiation. And the photocatalytic activities of the samples were evaluated on the removal of methylene blue under visible light irradiation. The N + S co-doped TiO 2 nanotube array films showed a better photocatalytic activity than the undoped sample due to the N, S doping.

Preparation of multiple-doped TiO2 nanotube arrays with nitrogen, carbon and nickel with enhanced visible light photoelectrochemical activity via single-step anodization

“…The increase in crystallinity may be due to the increased incorporation of the dopant atoms. Such a phenomenon has been previously reported by Yan et al upon doping TiO 2 with N and S atoms [52]. Using a concentration of 0.070 wt % for the tetracyanonickelate salt results in the reduction of the total peak intensity area of the anatase phase.…”

“…Generally speaking, the inter-band electron transition in TiO 2 semiconductors is accompanied with relaxation and recombination processes. As a result, a small part of the photons absorbed by TiO 2 contribute to the generation of a photocurrent [52,75]. We have performed photocurrent and photopotential measurements to determine the behavior of the transfer carriers and photon to current conversion abilities of our fabricated photoanodes.…”

Microwave-Assisted Hydrothermal Synthesis of TiO2Mesoporous Beads Having C and/or N Doping for Use in High Efficiency All-Plastic Flexible Dye-Sensitized Solar Cells

“…This is why the Ti 4+ /Ti 3+ ratio of HMT-200 is the lowest, otherwise a higher temperature would be expected to give a crystalline structure having less oxygen vacancies. The reduced Ti 4+ /Ti 3+ ratio can also be examined from the fact that the electronegativity of nitrogen is lower than that of oxygen, leading to an increased electron density around the Ti cation 26,27 and hence a higher Ti 3+ concentration. The peak at 399.5 eV is related to interstitial nitrogen doping (Ti-O-N).…”

Sulfur-doped TiO2 nanocrystalline photoanodes for dye-sensitized solar cells

“…Figure 2 shows the S2p of sulfur-doped TiO 2 and un-doped TiO 2 ; two peaks were observed around 168.4 and 169.5 eV for the sulfur-doped TiO 2 while almost no trace of sulfur based species was in un-doped TiO 2. According to the previous studies [14][15][16][17][18][19] the peak of 168.4 and 169.5 eV were S 6þ absorption peak. It should be noted that no peaks were found around 162 eV, which corresponds to the S 2À species.…”