Recent Studies on the Catalytic Activity of Titanium, Zirconium, and Hafnium Oxides

Salem, Ibrahim A.

doi:10.1081/cr-120015740

Cited by 91 publications

(30 citation statements)

References 132 publications

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“…22,23 TiO 2 , ZrO 2 , and HfO 2 oxides have also been utilized to catalyze the aromatization of C 6+ alkanes. 20 While chemical reactions of the bare transition metal oxide cations with H 2 have received a significant interest, [24][25][26][27][28][29][30][31][32][33][34][35][36][37] neutral metal oxides have gained much less attention. [38][39][40][41][42][43][44][45][46][47][48][49][50] Recently Zhou et al 51 have reported a combined experimental and theoretical study on the hydrogenation reactions by group V metal dioxides using matrix isolation spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, ZrO 2 is a well known solid acid-catalyst 20 and as a result, the mixture of TiO 2 -ZrO 2 oxides has excellent catalytic properties showing interesting acid-base surface properties, high surface area, great thermal stability and strong mechanical strength. 21 Additionally, HfO 2 has recently been used to replace the SiO 2 gate dielectric due to its high dielectric constant in order to further miniaturize microelectronic components in metal oxides semiconductors.…”

Section: Introductionmentioning

confidence: 99%

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How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

González-Navarrete

Andrés

Berski

2012

J. Phys. Chem. Lett.

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A theoretical investigation using density functional theory (DFT) has been carried out in order to understand the molecular mechanism of dihydrogen activation by means of transition metal dioxides MO 2 (M = Ti, Zr and Hf), according to the following reaction: MO 2 + H 2 → MO + H 2 O. B3LYP/6-311++G(2df,2pd)/SDD methodology was employed considering two possible reaction pathways. As first step the hydrogen activation by M=O bonds yields to metal-oxo hydride intermediates O=MH(OH). This process is spontaneous for all metal dioxides, and the stability of the O=MH(OH) species depends on the transition metal center. Subsequently, the reaction mechanism splits into two paths; the first one takes place passing through the M(OH) 2 intermediates yielding to products whereas the second one corresponds to the direct formation of the product complex OM(H 2 O). A two state reactivity mechanism was found for TiO 2 system whereas for ZrO 2 and HfO 2 no spin-crossing processes were observed. This is confirmed by CASSCF/CASPT2 calculations for ZrO 2 that lead to the correct ordering of electronic states not found by DFT. The results obtained in the present paper for MO 2 molecules are consistent with the observed reactivity on surfaces.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

González-Navarrete

Andrés

Berski

2012

J. Phys. Chem. Lett.

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“…Due to the consequence of the ion-exchangable nature of the TiO 2 nanotube structure, TiO 2 nanotubes surface-modified by the Zn 2+ ions facilitate the charge separation, which results in a further improvement of the photocatalytic activity for the degradation of methyl orange in water [18,19]. In addition, ZnS nanoparticles have distinct catalytic functions as compared with TiO 2 [20,21]. These effects are favorable for the improvement of the degradation efficiency of TiO 2 /ZnS nanocomposites.…”

Section: Resultsmentioning

confidence: 94%

Preparation of TiO2/ZnS core/sheath heterostructure nanotubes via a wet chemical method and their photocatalytic activity

Zhu

Feng

et al. 2007

React Kinet Catal Lett

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TiO 2 /ZnS core/sheath heterostructure nanotubes are prepared via a simple wet chemical method at room temperature. The samples are characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectrum. Their photocatalytic activity for degradation of methyl orange under UV illumination is valuated. It is found that the ZnS layer changes with the concentration of precursors. The photocatalytic activity of the TiO 2 /ZnS depends not only on the structure of the support (TiO 2 nanotubes) but also on the specific interaction between ZnS and support.

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“…Many semiconductors have photocatalytic properties [6][7][8], the nano titanium dioxide (TiO 2 ) appears the most efficient and popular photocatalyst [9] because of its outstanding photocatalytic activity, inertness [10], its stability within a wide range of pH [7], and inexpensive photosensitized material [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of Lamp Power and Its Position on Photocatalytic Degradation of Phenol in Aqueous Suspension of TiO2

Naeem

Ouyang

2009

e-J. Surf. Sci. Nanotechnol.

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The photocatalytic degradation of phenol under irradiation with UV light was investigated in aqueous suspension of nano titanium dioxide (TiO2). The effects of photocatalyst such as TiO2 (anatase) and TiO2-P25 and power of UV-lamp along with position on the photocatalytic degradation of phenol have been studied. The degradation kinetics was analyzed by the change in phenol absorbance employing UV-vis spectrometry as a function of irradiation time. The degradation follows first order kinetics. TiO2-P25 was found to be more reactive than TiO2 (anatase) which is attributed to small crystalline size. Horizontal position of the lamp was found to be better than vertical position of lamp. The degradation was also enhanced with increased in power of UV lamp.

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Recent Studies on the Catalytic Activity of Titanium, Zirconium, and Hafnium Oxides

Cited by 91 publications

References 132 publications

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

Preparation of TiO2/ZnS core/sheath heterostructure nanotubes via a wet chemical method and their photocatalytic activity

Effect of Lamp Power and Its Position on Photocatalytic Degradation of Phenol in Aqueous Suspension of TiO2

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