Self-Doped Ti3+ Enhanced Photocatalyst for Hydrogen Production under Visible Light
05 Aug 2010-Journal of the American Chemical Society (American Chemical Society)-Vol. 132, Iss: 34, pp 11856-11857
TL;DR: The UV-vis spectra show that the Ti(3+) here extends the photoresponse of TiO(2) from the UV to the visible light region, which leads to high visible-light photocatalytic activity for the generation of hydrogen gas from water.
Abstract: Through a facile one-step combustion method, partially reduced TiO2 has been synthesized. Electron paramagnetic resonance (EPR) spectra confirm the presence of Ti3+ in the bulk of an as-prepared sample. The UV−vis spectra show that the Ti3+ here extends the photoresponse of TiO2 from the UV to the visible light region, which leads to high visible-light photocatalytic activity for the generation of hydrogen gas from water. It is worth noting that the Ti3+ sites in the sample are highly stable in air or water under irradiation and the photocatalyst can be repeatedly used without degradation in the activity.
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TL;DR: Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting and its Applications d0 Metal Oxide Photocatalysts 6518 4.4.1.
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References
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TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.
11,402 citations
TL;DR: A chemically modified n-type TiO2 is synthesized by controlled combustion of Ti metal in a natural gas flame and performs water splitting with a total conversion efficiency of 11% and a maximum photoconversion efficiency of 8.35% when illuminated at 40 milliwatts per square centimeter.
Abstract: Although n-type titanium dioxide (TiO2) is a promising substrate for photogeneration of hydrogen from water, most attempts at doping this material so that it absorbs light in the visible region of the solar spectrum have met with limited success. We synthesized a chemically modified n-type TiO2 by controlled combustion of Ti metal in a natural gas flame. This material, in which carbon substitutes for some of the lattice oxygen atoms, absorbs light at wavelengths below 535 nanometers and has a lower band-gap energy than rutile (2.32 versus 3.00 electron volts). At an applied potential of 0.3 volt, chemically modified n-type TiO2 performs water splitting with a total conversion efficiency of 11% and a maximum photoconversion efficiency of 8.35% when illuminated at 40 milliwatts per square centimeter. The latter value compares favorably with a maximum photoconversion efficiency of 1% for n-type TiO2 biased at 0.6 volt.
3,911 citations
TL;DR: A review of the known inorganic catalysts with a focus on structure-activity relationships is given in this article, where the first water splitting system based on TiO2 and Pt was proposed by Fujishima and Honda in 1972.
Abstract: Photochemical splitting of water into H2 and O2 using solar energy is a process of great economic and environmental interest. Since the discovery of the first water splitting system based on TiO2 and Pt in 1972 by Fujishima and Honda, over 130 inorganic materials have been discovered as catalysts for this reaction. This review discusses the known inorganic catalysts with a focus on structure–activity relationships.
1,977 citations
1,925 citations
TL;DR: In this paper, the infrared absorption of a series of plane parallel plates having electrical resistivities ranging from 3 to 0.01 ohm-m has been examined and it is postulated that the electrical conductivity arises from the ionization of either one or two trapped electrons from each oxygen vacancy.
Abstract: Rutile Ti${\mathrm{O}}_{2}$ single crystal plates have been reduced in hydrogen at about 700\ifmmode^\circ\else\textdegree\fi{}C for several minutes to make them semiconducting. The concentration of oxygen vacancies was controlled by variations of time and temperature. The infrared absorption of a series of plane parallel plates having electrical resistivities ranging from 3 to 0.01 ohm-m has been examined. It is postulated that the electrical conductivity arises from the ionization of either one or two trapped electrons from each oxygen vacancy.In samples with electrical resistivity (\ensuremath{\perp} to the $c$ axis) greater than 0.04 ohm-m, the optical absorption at room temperature peaks at about 0.75 ev. For samples with electrical resistivity less than 0.03 ohm-m, the optical absorption shows a new maximum at 1.18 ev. The decrease of thermal activation energy with increasing oxygen vacancy concentration is expected to explain the "optical transition" from 0.75 to 1.18 ev. The ionization energies agree reasonably well with those calculated for a helium atom model of a doubly ionizable donor immersed in a dielectric medium [${K}_{e}={{n}_{o}}^{2}={(2.40)}^{2}$], namely 0.73 ev and 1.64 ev. A modification of this theory is also indicated which predicts the second ionization energy as 1.41 ev in better agreement with the experimental value of 1.18 ev.
602 citations