ATR-FTIR measurements and quantum chemical calculations concerning the adsorption and photoreaction of oxalic acid on TiO2

Mendive, Cecilia B.; Bredow, Thomas; Blesa, Miguel A.; Bahnemann, Detlef W.

doi:10.1039/b518007b

Cited by 108 publications

(136 citation statements)

References 63 publications

(110 reference statements)

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“…The stretch at 1590 cm −1 is due to -COOH conjugated to a nanoparticle whereas that at 1720 cm −1 is due to free, i.e., unconjugated -COOH. Red shift by ∼130 cm −1 in conjugated -COOH had been also observed in various metal oxide nanoparticles, [21][22][23][24] supporting our result. The weight percents of surface coated PEG diacid were estimated to be 53 and 66% for samples 1 and 2, respectively, from TGA curves as shown in Figure 4.…”

Section: B Surface Coatingsupporting

confidence: 77%

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

Choi

Baek

et al. 2013

AIP Advances

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Two samples of ultra small Gd(III) doped iron oxide nanoparticles were prepared to investigate Gd(III) doping effect on longitudinal (r1) and transverse (r2) water proton relaxivities. Gd(III) doping mole percents were 0.2 and 0.4 for samples 1 and 2, respectively. Average particle diameters were 2.5 to 2.1 nm for samples 1 and 2, respectively. Reduced r1 and r2 values were observed in both samples. We attributed this to reduced magnetizations arising from opposing effect of Gd(III) to net magnetizations of Fe(III)/Fe(II) in oxide nanoparticles

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Section: B Surface Coatingsupporting

confidence: 77%

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

Choi

Baek

et al. 2013

AIP Advances

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“…Bonding structures between either amino acid or dicarboxylic acid groups and metal oxide nanoparticles has been spectroscopically well characterized by other groups. [18][19][20][21] According to their results, the oxygen atoms of the carboxylic group chemically bind to the surface metal ions, which can be confirmed by the redshifted C=O stretches. Note that the C=O stretches of the surface coating ligands used in this work, i.e.…”

Section: Metal Surfacementioning

confidence: 54%

Water‐Soluble Ultra Small Paramagnetic or Superparamagnetic Metal Oxide Nanoparticles for Molecular MR Imaging

et al. 2009

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“…[23] Therefore, these model calculations correspond to well-defined single-crystal surfaces, and not to nanoparticles. Recently, sophisticated experiments on commercial powders have been performed, [24] and thus there is a growing need for precise microstructural investigations on exactly these powders. The poor knowledge of the real shape of commercial anatase powder particles forces researchers to catch at a straw and rely on data gained on arbitrary synthesis or even on macroscopic anatase crystals.…”

mentioning

confidence: 99%

Direct Measurement of Size, Three‐Dimensional Shape, and Specific Surface Area of Anatase Nanocrystals

et al. 2007

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At the heart of photocatalysis lies the recognition that chemical reactions are catalyzed on specific surfaces of catalyst particles. Because of the specific structure of such particles and the coordination of exposed surface atoms, the reactivity of different surfaces and their mechanisms for bonding to adsorbed molecules can vary dramatically. [1,2] Information about the size and shape of titanium dioxide (TiO 2 ) nanocrystals and, in particular, about the abundance and relative surface areas of specific crystal facets is highly desirable for the development of sophisticated photocatalytic experiments that are based on powdery materials. Unfortunately, for real catalysts, the kind of crystal facets that are exposed and their relative abundances are often not known. Profound knowledge about the relationship between processing conditions and the abundance of specific crystal facets would allow for tailoring improved catalysts that show predominantly those surfaces that are catalytically most active for specific reactions. The discovery of the decomposition of water on TiO 2 electrodes [3] stimulated many further investigations and opened up the research area of photocatalysis. Today, titanium dioxide is by far the most important photocatalyst material. It is commercially available as powders in two crystalline modifications, anatase and rutile, with surface areas ranging from 10 to more than 300 m 2 g À1. There is some evidence that the surface energy densities of anatase are generally lower than those of rutile. [4][5][6] However, theoretical predictions of the relative stability of perfect rutile and anatase surfaces do not give a coherent picture. Depending on the quantum-chemical method, the calculated rutile (110) surface energy density is found to be smaller [7] or larger [8,9] than those of all anatase low-index surfaces. Calculations based on classical pair potentials [6,10] disagree as to the relative stability of different anatase surfaces. All of these theoretical calculations are for perfect clean TiO 2 surfaces. A study for water-covered surfaces predicts anatase (101) and anatase (100) to be more stable than rutile (110), depending on the coverage with hydrogen or oxygen. [5] In another theoretical study of rutile and anatase nanoparticles of 2-6 nm diameter, [11] it was concluded that anatase particles have smaller surface energy densities than rutile up to a diameter of 2.5 nm. Consequently, for small crystals that show high surface-tovolume ratios, it is advantageous to adopt the anatase modification, and large titania crystals are thermodynamically favored if they have the rutile structure. The rutile-to-anatase transition occurs at particle sizes of a few tens of nanometers, and it depends on temperature, grain size, nanocrystal morphology, impurity content, reaction atmosphere, and synthesis conditions. [5,12]

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ATR-FTIR measurements and quantum chemical calculations concerning the adsorption and photoreaction of oxalic acid on TiO2

Cited by 108 publications

References 63 publications

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

Water‐Soluble Ultra Small Paramagnetic or Superparamagnetic Metal Oxide Nanoparticles for Molecular MR Imaging

Direct Measurement of Size, Three‐Dimensional Shape, and Specific Surface Area of Anatase Nanocrystals

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