New hollandite oxides: TiO2(H) and K0.06TiO2

Latroche, M.; Brohan, Luc; Marchand, R.; Tournoux, M.

doi:10.1016/0022-4596(89)90204-1

Cited by 133 publications

(84 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Besides these polymorphs, two additional high-pressure forms have been synthesized from the rutile phase. These are TiO 2 (II) [29] with a PbO 2 structure and TiO 2 (H) [30] with a hollandite structure. In this review, only the crystal structures (Table 1) [31][32][33] and properties of the rutile, anatase and brookite polymorphs are considered.…”

Section: Chemical Structure Of Tiomentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

View full text Add to dashboard Cite

Climate change and the consumption of non-renewable resources are considered as the greatest problems facing humankind. Because of this, photocatalysis research has been rapidly expanding. TiO 2 nanoparticles have been extensively investigated for photocatalytic applications including the decomposition of organic compounds and production of H 2 as a fuel using solar energy. This article reviews the structure and electronic properties of TiO 2 , compares TiO 2 with other common semiconductors used for photocatalytic applications and clarifies the advantages of using TiO 2 nanoparticles. TiO 2 is considered close to an ideal semiconductor for photocatalysis but possesses certain limitations such as poor absorption of visible radiation and rapid recombination of photogenerated electron/hole pairs. In this review article, various methods used to enhance the photocatalytic characteristics of TiO 2 including dye sensitization, doping, coupling and capping are discussed. Environmental and energy applications of TiO 2 , including photocatalytic treatment of wastewater, pesticide degradation and water splitting to produce hydrogen have been summarized. Historical backgroundThe growth of industry worldwide has tremendously increased the generation and accumulation of waste byproducts. In general, the production of useful products has been focused on and the generation of waste byproducts has been largely ignored. This has caused severe environmental problems that have become a major concern. Researchers all over the world have been working on various approaches to address this issue. Photoinduced processes have been studied and various applications have been developed. One important technique for removing industrial waste is the use of light energy (electromagnetic radiation) and particles sensitive to this energy to mineralize waste which aids in its removal from solution. Titanium dioxide (TiO 2 ) is considered very close to an ideal semiconductor for photocatalysis because of its high stability, low cost and safety toward both humans and the environment.*Corresponding author (email: shipra.mital@gmail.com)In 1964, Kato et al.[1] published their work on the photocatalytic oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) by a TiO 2 suspension, which was followed by McLintock et al. [2] investigating the photocatalytic oxidation of ethylene and propylene in the presence of oxygen adsorbed on TiO 2 . However, the most important discovery that extensively promoted the field of photocatalysis was the "Honda-Fujishima Effect" first described by Fujishima and Honda in 1972 [3]. This well-known chemical phenomenon involves electrolysis of water, which is related to photocatalysis. Photoirradiation of a TiO 2 (rutile) single crystal electrode immersed in an aqueous electrolyte solution induced the evolution of oxygen from the TiO 2 electrode and the evolution of hydrogen from a platinum counterelectrode when an anodic bias was applied to the TiO 2 working electrode. In 1977, Frank and Bard [4] examined the reduction of ...

show abstract

Section: Chemical Structure Of Tiomentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

View full text Add to dashboard Cite

show abstract

“…The studies on the crystal structure of titanium oxides containing alkali elements are scarce. [25][26][27][28][29][30] TiO 2 nanoparticles doped with 5 % K and heated at 550°C were reported to have the anatase crystal structure. [25] Addition of an alkaline dopant was shown to affect the anatase-torutile transition temperature.…”

Section: Full Papermentioning

confidence: 99%

Long K‐Doped Titania and Titanate Nanowires on Ti Foil and FTO/Quartz Substrates for Solar‐Cell Applications

Cheung

Yip

Djurišić

et al. 2007

Adv Funct Materials

View full text Add to dashboard Cite

Potassium‐doped titania and titanate nanowires are fabricated by moisture‐assisted direct oxidation of titanium. The influence of the fabrication conditions on nanowire structure and morphology is investigated. It is shown that the presence of potassium is essential for nanowire formation, while the nanowire structure and morphology are strongly dependent on the fabrication temperature. The longest nanowires (ca. 10 μm) are obtained at 650 °C. At this substrate temperature, nanowires could be produced over a large substrate area both by oxidation of the Ti foil as well as by depositing a Ti film on the substrate (quartz or fluorine‐doped tin oxide (FTO)/quartz). Photovoltaic cells based on these nanowires are fabricated. The cell performance is dependent on the nanowire fabrication temperature and the substrate used, as well as on the annealing environment. Short‐circuit current densities of Isc = 3.05 mA cm–2 and Isc = 4.97 mA cm–2 could be obtained for Ti foil and FTO/quartz substrates, respectively, while the corresponding power‐conversion efficiencies are η = 0.93 % and η = 1.88 % (under AM 1.5 illumination, 100 mW cm–2; AM: air mass).

show abstract

“…Since interaction between the cations and hollandite-type TiO 2 framework is weak, the cations can be easily intercalated into and deintercalated from the tunnel with keeping intact the overall original structure. Because of the unique microporous feature, hollandite-type TiO 2 has been studied from the viewpoint of crystal structure 13 and application such as battery characteristics 14,15 and immobilization of radioactive elements. The hollandite-type TiO 2 framework is composed of edge and corner-shared TiO 6 octahedron as A and R-type TiO 2 structures are composed.…”

Section: Introductionmentioning

confidence: 99%

Room temperature ferromagnetic behavior in the hollandite-type titanium oxide

Noami

Muraoka

Wakita

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

A hollandite-type K x Ti 8 O 16 polycrystalline sample has been prepared and studied by magnetization, resistivity and x-ray photoelectron spectroscopy ͑XPS͒. Room temperature ferromagnetic behavior is observed in the magnetic hysteresis measurement. The sample shows a semiconductive temperature dependence in the resistivity measurement. Analysis of the Ti 2p 3/2 core-level XPS spectrum indicates that the titanium ions have a mixed valence of Ti 4+ and Ti 3+ . In addition, the valence band spectrum reveals that the 3d electrons tend to localize on Ti 3+ ions in the hollandite-type TiO 2 lattice. Also, analysis of the valence band spectrum shows that the prepared sample is a wide-gap oxide with a band gap of 3.6 eV. These results indicate that the present hollandite-type K x Ti 8 O 16 sample can be classified as a TiO 2 -based wide-gap semiconductor with Curie temperature above room temperature. Room temperature ferromagnetism ͑RTFM͒ decreases in the sample prepared under a strong reducing gas atmosphere, accompanied with the decrease in the resistivity. The results imply that the localized 3d electrons are responsible for the RTFM of the K x Ti 8 O 16 sample.

show abstract

New hollandite oxides: TiO2(H) and K0.06TiO2

Cited by 133 publications

References 19 publications

A review of TiO2 nanoparticles

A review of TiO2 nanoparticles

Long K‐Doped Titania and Titanate Nanowires on Ti Foil and FTO/Quartz Substrates for Solar‐Cell Applications

Room temperature ferromagnetic behavior in the hollandite-type titanium oxide

Contact Info

Product

Resources

About