Luminescence mechanism of ZnO thin film investigated by XPS measurement

Hsieh, Pei-Shan; Chen, Y. C.; Kao, K. C.; Wang, C. M.

doi:10.1007/s00339-007-4275-3

Cited by 525 publications

(240 citation statements)

References 34 publications

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“…7. In all cases studied, the obtained O1s asymmetric peak was coherently fitted with three components in agreement with previously reported studies [38]. Accordingly, the oxygen species on the lowest side of the O 1s spectrum labelled as Oa can be attributed to Zn-O bonds of highly crystalline ZnO.…”

Section: Xps Study Of Oxygen Vacancies In Zno Supportssupporting

confidence: 90%

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Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Eblagon

Concepción

Silva

et al. 2014

Applied Catalysis B: Environmental

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The influence of the calcination atmosphere of ZnO precursor (Zn4(CO)3(OH)6·H2O) on the catalytic performance of a series of PdZn/ZnO catalysts was studied for production of H2 via low temperature (180 • C) direct methanol steam reforming (low temperature-MSR). The catalytic activity and selectivity of PdZn/ZnO were found to be strongly influenced by the calcination atmosphere of ZnO precursor and increased from oxidizing to reducing atmosphere, following the order (O2 < air < N2 < H2). As a result, a very active catalyst was obtained by simply supporting Pd on ZnO calcined in H2. Further evidence from XPS and TPR analysis indicated that calcination in reducing atmosphere gave rise to a significant increase in the concentration of oxygen vacancies on the surface of ZnO support. Thus, the superb performance of the best catalyst was attributed to the defect chemistry of ZnO support; mainly to the amount of oxygen vacancies present in the interface region, which act as additional active sites for water adsorption and subsequent activation. In addition, the formation of CO was drastically suppressed by replenishment of oxygen vacancies on ZnO support. Thus, it is clear that the abundance of specific active sites on PdZn/ZnO catalyst is strongly influenced by the preparation route of the ZnO support. Additionally, the PdZn alloy was discovered to be unstable under prolonged exposure to CO atmosphere and the stability test under methanol steam reforming conditions showed a 24% drop in conversion over 48 h testing period. This phenomena can have detrimental effect on the performance of this type of catalytic systems in continuous prolonged duty cycle time on-stream.

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Section: Xps Study Of Oxygen Vacancies In Zno Supportssupporting

confidence: 90%

“…Different amount of oxygen vacancies in ZnO supports was also confirmed by studying the Auger line of Zn LMM. The BE of Auger Zn LMM is generally more sensitive to the chemical environment [38]. As shown in Fig.…”

Section: Xps Study Of Oxygen Vacancies In Zno Supportsmentioning

confidence: 97%

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Eblagon

Concepción

Silva

et al. 2014

Applied Catalysis B: Environmental

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“…The peak localized at lower energy is usually attributed to O 2-ions in the wurtzite crystal structure of hexagonal ZnO lattice (Tam et al 2006). The peak at higher energy, on the other hand, usually is reported to result from the presence of loosely bound oxygen or OH -species on the surface, or O 2-ions in the oxygen deficient regions (Hsieh et al 2008). The intensity of this defectrelated peak decreases significantly after etching.…”

Section: Morphology and Structurementioning

confidence: 99%

Hydrothermal–electrochemical growth of heterogeneous ZnO: Co films

Yilmaz

Ünal

2017

Appl Nanosci

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This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermalelectrochemical deposition at 130°C and -1.1 V (vs Ag/ AgCl (satd)) in dimethyl sulfoxide (DMSO)-H 2 O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.

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“…The O 1s spectra of ZnO NPs can be described as the superposition of two Gaussian peaks. The main peak, at about 530.1 ± 0.1 eV, is attributed to oxygen in the ZnO crystal lattice (O L ) [39,40], while the The XPS data of Zn 2p and O 1s of the vacuum-treated and pristine ZnO NPs are shown in Table 2. As the atomic ratio of Zn to OL at the surface of the samples is much higher than 1.0, this suggests that there are many oxygen vacancies at the surface of the ZnO NPs.…”

Section: Xps Analysismentioning

confidence: 99%

“…The O 1s spectra of ZnO NPs can be described as the superposition of two Gaussian peaks. The main peak, at about 530.1 ± 0.1 eV, is attributed to oxygen in the ZnO crystal lattice (OL) [39,40], while the second peak, at a higher binding energy (OH) of 532.0 ± 0.1 eV, is related to the presence of hydroxyl groups (-OH) [37]. smaller than those (~200 nm) of Sample A, owning to a decrease in particle aggregation-the smaller the particle size, the larger the specific surface area.…”

Section: Xps Analysismentioning

confidence: 99%

Oxygen Vacancy-Mediated ZnO Nanoparticle Photocatalyst for Degradation of Methylene Blue

et al. 2018

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Featured Application: Photocatalyst for degradation of dyes.Abstract: ZnO nanoparticles (NPs) are synthesized by deoxidizing ZnO powder in a vacuum drying process. This process reduces the size of the NPs and increases the concentration of oxygen vacancies on their surfaces. ZnO NPs with sufficient oxygen vacancies are highly effective for the photodecomposition of methylene blue (MB) dye in water under ultraviolet irradiation. The MB degradation efficiency exceeds 99 percent after 50 min of light irradiation, and the catalytic property of the NPs remains stable over several complete degradation cycles. It is revealed that the concentration of oxygen vacancies on the surface, and the photocatalytic activity, are both higher for smaller NPs. Oxygen vacancies reduce the recombination rate of photo-generated charge carriers by capturing the electrons and hence, improve the efficiency of redox reactions. In addition, a smaller particle size leads to a larger specific surface area and a higher photonic efficiency for the ZnO NPs.

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Luminescence mechanism of ZnO thin film investigated by XPS measurement

Cited by 525 publications

References 34 publications

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Hydrothermal–electrochemical growth of heterogeneous ZnO: Co films

Oxygen Vacancy-Mediated ZnO Nanoparticle Photocatalyst for Degradation of Methylene Blue

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