Induced zinc desorption from zinc oxide during exposure to a reducing agent

Krummel, C.; Freiling, A.; Schmidt, Ralf; Kelleter, J.; Wollnik, H.; Kohl, Claus-Dieter

doi:10.1007/bf00321314

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…Due to its semiconducting and optical properties, it is used as a front electrode in thin-film solar cells and as a sensor for hydrogen. [1][2][3][4][5][6] ZnO nanoparticles are applied to improve the properties of rubber 7 and also frequently in heterogeneous catalysis. ZnO is an essential component of the ternary copper-based catalysts for the modern low-pressure methanol synthesis process, in which carbon monoxide, carbon dioxide, and hydrogen are converted into methanol, the third-most large-scale chemical product.…”

Section: Introductionmentioning

confidence: 99%

“…Zinc oxide is an important functional material, which is applied in different fields for various purposes. Due to its semiconducting and optical properties, it is used as a front electrode in thin-film solar cells and as a sensor for hydrogen. – ZnO nanoparticles are applied to improve the properties of rubber and also frequently in heterogeneous catalysis. ZnO is an essential component of the ternary copper-based catalysts for the modern low-pressure methanol synthesis process, in which carbon monoxide, carbon dioxide, and hydrogen are converted into methanol, the third-most large-scale chemical product. , ZnO is also a catalyst for the water gas shift reaction, converting carbon monoxide with water into carbon dioxide and hydrogen …”

Section: Introductionmentioning

confidence: 99%

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Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry. 1. The Influence of the Thermal Pretreatment on the Adsorption of Carbon Dioxide

et al. 2008

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The adsorption of carbon dioxide on differently pretreated polycrystalline ZnO was studied by thermodynamic and kinetic methods. The uptake of CO 2 observed in a static Tian-Calvet microcalorimeter reached saturation at about 5 µmol/m 2 , corresponding to about half of the exposed Zn 2+ sites after a thorough thermal pretreatment at 450 °C for 4 h. The saturation uptake was found to be correlated inversely with the amount of residual hydroxyl groups on the ZnO surfaces. At room temperature, the adsorption of CO 2 was found to occur in two steps. Initially, the adsorption was nonactivated, and the exposed surfaces were saturated at a very low equilibrium pressure (p , 1 Pa) with an initial differential heat of adsorption (q diff ) of 100-120 kJ/mol, a standard entropy of -190 J mol -1 K -1 , and an adsorption rate constant of 10 -5 Pa -1 s -1 . During the second stage, an inhibiting effect was observed; the equilibrium coverage increased slowly with increasing pressure, q diff decreased rapidly with increasing coverage, and the rate of adsorption was low. Temperature-programmed desorption measurements indicated the formation of strongly adsorbed polydentate carbonates at higher temperatures with an adsorption energy between 120 and 160 kJ/mol.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry. 1. The Influence of the Thermal Pretreatment on the Adsorption of Carbon Dioxide

et al. 2008

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“…1,2 ZnO is frequently used as gas sensor for hydrogen and carbon hydrides since the surface conductivity of the zinc oxide varies with gas pressure. [3][4][5] Zinc oxide is used as a support in relevant technological processes involving heterogeneous catalysis. It acts, for example, as a support for copper nano particles for methanol synthesis from synthesis gas, 6 for the water gas shift reaction 7 and for steam reforming.…”

Section: Introductionmentioning

confidence: 99%

Water adsorption on the hydroxylated H-(1 × 1) O-ZnO(0001̄) surface

Schiek

Al‐Shamery

Kunat

et al. 2006

Phys. Chem. Chem. Phys.

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The adsorption of water multilayers on a well defined single crystal, hydroxyl-terminated ZnO-surface, H(1x1)-O-ZnO(0001) surface has been investigated using infrared (IR) spectroscopy, helium atom scattering (HAS) and X-ray photoelectron spectroscopy (XPS). The results reveal the formation of well ordered mono-, bi- and multilayers of D2O and H2O on this substrate. On the bare hydroxyl-covered H(1x1) surface the OH-stretch vibration could be clearly identified in the IR-spectra. The water adsorption and desorption kinetics on this hydroxylated surface were studied by monitoring the reflectivity of the surface for helium atoms. The analysis of the data yielded activation energies for desorption of H2O from the H(1x1) O-ZnO surface of 55.2 kJ mol-1. The results reveal the formation of ordered mono- and bilayers. Further exposure to water at 113 K results in the formation of amorphous 3-D islands.

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“…According to Wo et al [37] transparent conducting oxide (TCO) layers are suitable to be used as front electrodes in thin film solar cells [38,39]. ZnO has also been used as a sensor for hydrogen and carbon hydrides since the conductivity of thin zinc oxide films varies considerably with hydrogen gas pressure [40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Effects of Moderate Amounts of Sulfur Substitutional Impurities on ZnO Using Density Functional Theory

Flores-Hidalgo¹

2011

TONANOJ

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A theoretical study on the effects of a moderate amount of sulfur when used as substituent impurity in place of oxygen in zinc oxide at its crystal form using Density Functional Theory (DFT). S-substituent amounts in percent go from 0.1% up to 1.0% and we analyze modifications in the crystal properties such as lattice characteristics, total energy, and gap energy. Lattice parameter c increased slightly as S-substituent percent increased, lattice parameter a had an opposite behavior because it decreased as the S-substituent increased and c/a rate had ups and downs but with very slight variation between consecutive values. Total energy calculations showed an increasing trend at all times and binding energy showed a decreasing trend at all times as the substituent percent increase but the variation between consecutive points was small. Gap energy had a decreasing trend with a maximum variation of 6.57% at 1.0% S-substituent from pristine ZnO. To correct DFT underestimation of gap energy we applied a correction factor and found a decreasing trend as the substituent percent increase and observed the highest difference from undoped ZnO was 1.42% at 1.0%S-substituent. We study the effects on the ZnO structure occurring when moderate S-substituent amounts from 0.1% to 1.0% are used and provide new knowledge to predict if the geometric and electronic structure changes may be suitable for new applications of ZnO in opto-electronics.

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Induced zinc desorption from zinc oxide during exposure to a reducing agent

Cited by 4 publications

References 5 publications

Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry. 1. The Influence of the Thermal Pretreatment on the Adsorption of Carbon Dioxide

Probing the Surface Heterogeneity of Polycrystalline Zinc Oxide by Static Adsorption Microcalorimetry. 1. The Influence of the Thermal Pretreatment on the Adsorption of Carbon Dioxide

Water adsorption on the hydroxylated H-(1 × 1) O-ZnO(0001̄) surface

Effects of Moderate Amounts of Sulfur Substitutional Impurities on ZnO Using Density Functional Theory

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