A Low-Band Gap, Nitrogen-Modified Titania Visible-Light Photocatalyst

Abstract

Bi 3 YO 6 , which is known as an ionic conductor, was tested here as an electrode and photoanode in contact with aqueous electrolytes. Bi 3 YO 6 was deposited onto the Pt substrate and the such prepared electrode was polarized in various aqueous electrolytes. The optical energy band gap of the material equal to 1.89 eV was determined using the Kubelka-Munk function resulting from the UV-Vis spectrum (allowed indirect transition) and also was calculated using the semi-empirical PM7 method (3.38 eV of HOMO-LUMO energy gap). Despite the yellow color of Bi 3 YO 6 , the tested material exhibits photoelectroactivity only in the UV range of electromagnetic radiation. The anodic photocurrent characteristic for n-type metal oxide semiconductors was recorded. The electrode exhibits diffusion-controlled cathodic activity while polarized in chloride-free aqueous electrolytes.

Decahedral-shaped anatase titania photocatalyst particles: Synthesis in a newly developed coaxial-flow gas-phase reactor

“…Simultaneously, argon (Ar; 75 mL min -1 ) was passed through the vaporizer as the carrier gas for TiCl 4 vapor. was wrapped with platinum foil (3 cm in width) (6) and heated by infrared lamps. A thermocouple was connected to the platinum foil, and the intensity of the infrared light was regulated precisely by the temperature controller.…”

“…Secondly, the recombination of photoexcited charge carriers (electron (e -)-holes (h + )), which reduces quantum efficiency, has not been controlled [3]. Many studies have been performed to obtain visible light activity by modification of titania with metal and non-metal elements [4][5][6][7]. The second limitation can be overcome by surface modification of titania with noble metals and their compounds that inhibit the charge recombination by increasing the transfer of photoexcited electrons from titania to substrates [5,[8][9][10].…”

Photocatalytic production of hydrogen on Ni/NiO/KNbO3/CdS nanocomposites using visible light

“…However, the majority of the simple and mixed-metal oxides photocatalysts are primarily active for H 2 production under UV irradiation (l < 385 nm or E g $ 3.0 eV) present in only a small portion of solar light. More recently, there is a focused effort on the development of photocatalysts that are capable of using visible light (l ¼ 400-700 nm) for the photocatalytic production of H 2 including transition metal doping (e.g., platinum, 29 chromium, 30 and vanadium 31 ) and nonmetallic element doping (e.g., nitrogen, [32][33][34][35] sulfur, 36,37 and carbon 35,38 ). CdS, n-type semiconductor with E g ¼ 2.4 eV, has been shown to have photocatalytic activity for H 2 production under visible light irradiation, although, sacrificial electron donors such as C 2 H 5 OH, 39 HS À , 40,41 or SO 3 2À 19 are used to obtain measurable rates of H 2 production and to avoid the photocorrosion of CdS in the presence of O 2 .…”

Synthesis and characterization of nitrogen and zirconium ions doped TiO2 films for photocatalytic application

“…There is no definite opinion about the XPS measurements of N1s binding energy where the values of 396-397 eV are assigned to the N-Ti-N [8] or O-Ti-N bonds [9]. The formation of N-N or N-C or N-O groups or chemisorbed dinitrogen is suggested at higher energies of 400-403 eV [9,11,25]. Nitrogen 1s binding energies of 399.2 and 400.5 eV are measured for a mixture of solid urea and TiO 2 powder calcined at 400 °C corresponded to carbon nitrides (399-400 eV, C=N-C) and similar graphite-like phases (400.6 eV, N-C sp2 ), and of polycyanogen (399.0, 400.5 eV (-C=N-) x ) [26].…”

“…[28]. The N1s peak with the maximum at 396.0 eV (Table 3) indicated the formation of substitutional nitrogen as namely Ti-N bonds in N/Zr/TiO 2 while the N1s peak of N/TiO 2 films at 400.6 eV could be related to the N-N or N-C, N-O or even chemisorbed dinitrogen species formation in TiO 2 matrix [11,25]. Note that N1s binding energies of 399.1 and 400.5 eV measured for modified by urea commercially available TiO 2 powder were assigned to carbon nitrides (399-400 eV, C=N-C), graphite-like phases (400.6 eV, N-Csp 2 ) and to polycyanogen (399.0, 400.5 eV (-C=N-) x ) [29].…”