The role of ionic point defects in the catalytic activity of ionic crystals

Simkovich, G.; Wagner, Carl G.

doi:10.1016/0021-9517(62)90124-0

Cited by 19 publications

References 2 publications

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“…[3], and uses the dependence of silver vacancy concentration [V Ag ¢ ] on the Cd 2+ (impurity/dopant) content in AgCl. In the bulk both concentrations are equal (Kro¨ger-Vink notation [4]):…”

Section: Example 1: Dehydrohalogenation Of T-butyl Chloridementioning

confidence: 99%

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The significance of defect chemistry for the rate of gas–solid reactions: three examples

Merkle

Maier

2006

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Three examples are revisited in which the reaction rate could be reliably correlated with point defect chemistry highlighting the role of point defects as acid-base active centers. In the case of dehydrohalogenation of tertiary butyl chloride, AgCl becomes increasingly active as heterogeneous catalyst, if AgCl is homogeneously or heterogeneously doped. By such a procedure the silver vacancy concentration is adequately increased. The oxygen incorporation into SrTiO 3 offers an example in which the surface mechanism in terms of adsorbed species, oxygen vacancies and electronic centers has been elucidated. Appropriate surface coatings give rise to significant catalytic effects. Increasing iron (acceptor) doping not only changes the point defect chemistry but also the nature of the rate determining step. Lastly, the electrocatalytic function of Sr-doped LaMnO 3 is considered as regards oxygen reduction reaction and O 2) incorporation into Y-doped ZrO 2 in the context of solid oxide fuel cells. Again the defect chemistry is of prime importance for the reaction rate.

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Section: Example 1: Dehydrohalogenation Of T-butyl Chloridementioning

confidence: 99%

“…increasing [Cd Ag AE ]) of CdCl 2 -doped AgCl as the catalyst. Figure adopted from Ref [3]. with permission from from Elsevier,…”

mentioning

confidence: 99%

The significance of defect chemistry for the rate of gas–solid reactions: three examples

Merkle

Maier

2006

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“…Point defects such as oxygen vacancies or redox-active dopants naturally represent catalytically active centers for surface reactions (see, e.g., ref. [30][31][32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Oxygen exchange kinetics on systematically doped ceria: a pulsed isotope exchange study

2019

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“…[31] These surface defects should, owing to their high local energy, be catalytically very reactive. In references [32] and [33] indeed the ability of these defects to be effective acid ± base catalytic centers has been demonstrated. Since for many reactions both acid/base and redox catalysis should be necessary, it is not surprising that mixed conductors are usually efficient catalysts (which may even be enhanced by the mobilities).…”

Section: Complicationsmentioning

confidence: 99%

Acid-Base Centers and Acid-Base Scales in Ionic Solids

Maier

2001

Chem. Eur. J.

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For the case of ionic crystals it is shown to be most straightforward and consistent to define acidity/basicity by the (electro-)chemical potential of the respective ion, in a similar fashion to the way that the Fermi level (i.e.. electrochemical potential of the electron) characterizes the redox state. The isomorphy is explicitly expressed by using the energy-level diagrams introduced for electrons in semiconductor physics. Without having to make further assumptions it is possible 1) to compare acidity/basicity between different solids, 2) to link internal and surface acidity/basicity, and 3) to establish acidity/basicity scales for ionic solids. The point defects are revealed to be the natural acidic and basic elementary centers, and associates between them to be the internal acids/bases exchanging these elementary centers. Even though acidity/basicity is an overall property of the solid, the number of point defects (if dilute) directly represents these properties in the same way as H+ or OH- accomplish this for aqueous solutions.

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The role of ionic point defects in the catalytic activity of ionic crystals

Cited by 19 publications

References 2 publications

The significance of defect chemistry for the rate of gas–solid reactions: three examples

The significance of defect chemistry for the rate of gas–solid reactions: three examples

Oxygen exchange kinetics on systematically doped ceria: a pulsed isotope exchange study

Acid-Base Centers and Acid-Base Scales in Ionic Solids

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