XPS and FTIR investigation of the surface properties of different prepared titania nano-powders

Jensen, Henrik; Soloviev, Alexei; Li, Zheshen; Søgaard, Erik Gydesen

doi:10.1016/j.apsusc.2004.11.015

Cited by 291 publications

(191 citation statements)

References 23 publications

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“…and 288.0 eV, assigned respectively to adventitious carbon, residual methoxide groups from the catalyst precursor, and carbonate groups. [81][82][83][84] The proportion of surface methoxide increased monotonically relative to the as calcined NanoMgO-700, even after exposure to low methanol doses (Fig. 3b).…”

Section: Scheme 3: Dissociation Of H2o Over Mg 2+ -O 2-dimersmentioning

confidence: 99%

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

et al. 2016

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An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O 2-sites to OH -and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C-H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects.Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production.

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Section: Scheme 3: Dissociation Of H2o Over Mg 2+ -O 2-dimersmentioning

confidence: 99%

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

et al. 2016

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“…The photon energies of synchrotron source can be varied to various escape depth of out coming photon electrons and having a better photon ionization cross-section [20]. Furthermore, the beam size of the synchrotron light source is much smaller than the conventional photon sources, which helps to reduce the effects of the non-uniformity of the sample surfaces [20]. Fig.…”

Section: Synchrotron Radiation Xps Studymentioning

confidence: 99%

Solar absorptance of copper–cobalt oxide thin film coatings with nano-size, grain-like morphology: Optimization and synchrotron radiation XPS studies

Amri

Duan

Yin

et al. 2013

Applied Surface Science

182

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Copper-cobalt oxides thin films had been successfully coated on reflective aluminium substrates via a facile sol-gel dip-coating method for solar absorptance study. The optimum absorptance in the range of solar radiation is needed for further optimum design of this material for selective solar absorber application. Field emission scanning electron microscopy was used to characterize the surface morphology of the coating whereby nano-size, grain-like morphology was observed.Synchrotron with dip-speed 120 mm/min (four cycles). The operational simplicity of the dip-coating system indicated that it could be extended for coating of other mixed metal oxides as well.

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“…H 2 O 2 can be produced by reaction of photoexcited electrons with molecular oxygen via superoxide anion (O 2 -) [23,24], and EPR studies have suggested the liberation of peroxide species in the presence of oxygen [6], though we have no information on the origin. Anatase TiO 2 samples of large specific surface area have been shown to have large amounts of hydroxyl groups and physisorbed water through studies of infrared spectroscopy [6,25], thermogravimetry [5,26,27] and 1 H NMR [28], and these species on Type 2 samples might participate in the hole trapping and/or peroxy species productions.…”

Section: Sb and Db Measurementsmentioning

confidence: 99%

Photoacoustic spectroscopic analysis of photoinduced change in absorption of titanium(IV) oxide photocatalyst powders: A novel feasible technique for measurement of defect density

Murakami

Mahaney

Torimoto

et al. 2006

Chemical Physics Letters

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Photoabsorption properties of titanium(IV) oxide powders were investigated by photoacoustic (PA) spectroscopy. The photoacoustic spectra obtained under steady-state ultraviolet irradiation showed appearance and growth of two kinds of PA signal bands, which were attributable to trivalent titanium species (Ti 3+ ) and trapped holes or surface peroxide species. The saturation limit of the PA signal was estimated by analyzing the time course of Ti 3+ signals and compared to the density of Ti 3+ determined by a photochemical method. The results suggest that the photoacoustic spectroscopic technique is a feasible alternative method for estimation of Ti 3+ as an empirical measure of defect density. * Corresponding

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XPS and FTIR investigation of the surface properties of different prepared titania nano-powders

Cited by 291 publications

References 23 publications

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

Solar absorptance of copper–cobalt oxide thin film coatings with nano-size, grain-like morphology: Optimization and synchrotron radiation XPS studies

Photoacoustic spectroscopic analysis of photoinduced change in absorption of titanium(IV) oxide photocatalyst powders: A novel feasible technique for measurement of defect density

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