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Huang, Ta-Jen

doi:10.1023/a:1023495223738

Cited by 233 publications

(108 citation statements)

References 12 publications

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“…In our reaction, the used catalyst shows evidence of CuO as well as Cu 2 O (Figure 2d,e), suggesting a mixed state of Cu + and Cu 2+ ; however surface Cu 2+ is an unlikely candidate for oxidation or O 2 dissociation. Consistent with previous reports for the bulk, 13 we believe the active catalyst state to be Cu + (in a Cu 2 O lattice) which is either present from the onset or formed by reduction of Cu 2+ by adsorbed CO. It is then thought that the CO combines with a surface oxygen to form CO 2 .…”

supporting

confidence: 91%

“…Oxygen is then supplied from the surface of the copper oxide and reacts with the CO to form CO 2 . 4,13,14,18 Aside from the oxidation state of copper, the oxygen concentration is an important factor in the oxidation process. It has been reported 3,19 that much of the CO oxidation work with copper uses an inert gas, such as N 2 , 1-2% CO, and 19% O 2 , which readily oxidizes the copper to CuO.…”

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confidence: 99%

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Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

et al. 2006

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We find that nearly monodisperse copper oxide nanoparticles prepared via the thermal decomposition of a Cu(I) precursor exhibit exceptional activity toward CO oxidation in CO/O 2 /N 2 mixtures. Greater than 99.5% conversion of CO to CO 2 could be achieved at temperatures less than 250°C for over 12 h. In addition, the phase diagram and pathway for CO oxidation on Cu 2 O (100) is computed by ab initio methods and found to be in qualitative agreement with the experimental findings.Nanoparticles offer a larger surface-to-volume ratio and a higher concentration of partially coordinated surface sites than the corresponding bulk materials. The unique properties of nanoparticles are due to a strong interplay between elastic, geometric, and electronic parameters, as well as the effects of interactions with the support. The result of these features is often improved physical and chemical properties compared to the bulk material. It is for these reasons that heterogeneous catalysis at nanoparticle surfaces is currently under intense investigation in the catalysis community at large. 1,2 Conventional supported catalysts are generally produced by impregnation of a support medium with the desired metal ions followed by thermal treatments that result in small and dispersed active catalytic sites. 3,4 Many traditional catalysts based on the impregnation method 5,6 rely on the noble metals, in particular platinum, as the source for high activity. Such metals are recognized as a scarce resource as well as a limiting step in the development of viable energy alternatives to petroleum. Automotive exhaust catalysts (the three way catalyst) and fuel cells are examples of this tenet. 5,6 Any new system that overcomes these limitations will be invaluable.There are several important processes in heterogeneous catalysis where removal of carbon monoxide is either desired or absolutely necessary, such as in the postprocessing of Syngas 7 to produce hydrogen as an energy source for use in fuel cells. 8,9 A byproduct of this reaction is CO; however, trace amounts of CO (>10 ppm) can poison a fuel cell electrode, drastically reducing its efficiency. [10][11][12] The CuCu 2 O-CuO system has been known to facilitate oxidation reactions in the bulk, suggesting it has potential as a costeffective substitute for noble metals in various catalytic systems. [13][14][15] Here we describe a cheap, effective method of using copper oxide nanoparticles loaded onto silica gel as an exceptional catalyst toward CO oxidation at relatively low temperatures. Over sustained periods of time, conversions of 99.5% of CO to CO 2 are routinely observed and the catalyst structure is retained during the reaction. For example, during a 50 h period with the same ∼10 mg sample of copper oxide nanoparticles, over 30 L of CO is converted to CO 2 with an average conversion of 98 ( 1%.With recent developments in nanoparticle synthesis leading to the ability to control size, reproducibility, and structural complexity, it becomes urgent to define specific target structu...

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confidence: 91%

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confidence: 99%

Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

et al. 2006

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“…In this study, the best catalyst was Au/5% CuO x -TiO 2 , somewhat different from that obtained by Haruta [2] for Au/TiO 2 , because different amount of gold were used; i.e., 1 wt% Au/TiO 2 in this study and 10 wt% Au/TiO 2 in their study [2]. Copper has various oxidation states, such as Cu 2 O and CuO, but Cu 2 O was found to be more active than CuO for CO oxidation [18].…”

Section: Xpscontrasting

confidence: 57%

Au/CuO<sub>x</sub>-TiO<sub>2</sub> Catalysts for CO Oxidation at Low Temperature

Duh¹,

Lee²,

Chen

2013

MRC

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A series of Au/CuO x -TiO 2 with various Cu/Ti ratios were prepared. CuO x /TiO 2 was prepared by incipient-wetness impregnation with aqueous solution of copper nitrate. Au catalysts were prepared by deposition-precipitation method at pH 7 and 338 K. The catalysts were characterized by inductively-coupled plasma-mass spectrometry, temperature programming reduction, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at WHSV of 120,000 mL/h·g. High gold dispersion and narrow size distribution was obtained. The addition of CuO x in Au/TiO 2 enhanced the activity on CO oxidation significantly. CuO x was in amorphous state which could stabilize the Au nanoparticles. Cu was in Cu 1+ state. Cu donated partial electrons to Au. The interactions among Au, Cu 1+ and TiO 2 account for the high catalytic activity for CO oxidation. The significant promotional effect of CuO x on CO oxidation at low temperature was demonstrated.

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“…Copper, CuO, and Cu 2 O are candidates to replace rare and expensive noble metal catalysts for applications including methane synthesis, [1][2][3] catalytic conversion of nitrogen oxides, 4 water-gas shift, 5,6 and preventing CO poisoning in fuel cells. 7,8 The mechanisms manifested in the early stages of copper oxidation are not well understood, especially under different environmental conditions. For example, using in situ ultrahigh vacuum transmission electron microscopy, Zhou and Yang found that the substrate temperature affects the morphology of the Cu 2 O islands that grow on the Cu(100) surface during oxidation, resulting in triangular, hut, rod, and pyramid shapes.…”

Section: Introductionmentioning

confidence: 99%

Ab initioatomistic thermodynamics study of the early stages of Cu(100) oxidation

Saidi

Lee

et al. 2012

Phys. Rev. B

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Using an ab initio atomistic thermodynamics framework, we identify the stable surface structures during the early stages of Cu(100) oxidation at finite temperature and pressure conditions. We predict the clean surface, the 0.25 monolayer oxygen-covered surface, and the missing-row reconstruction as thermodynamically stable structures in range of 100-1000 K and 10 −15 -10 5 atm, consistent with previous experimental and theoretical results. We also investigate the thermodynamic stabilities of possible precursors to Cu 2 O formation including missing-row reconstruction structures that include extra on-or subsurface oxygen atoms as well as boundary phases formed from two missing-row nanodomains. While these structures are not predicted to be thermodynamically stable for oxygen chemical potentials below the nucleation limit of Cu 2 O, they are likely to exist due to kinetic hindrance.

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Cited by 233 publications

References 12 publications

Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

Au/CuO<sub>x</sub>-TiO<sub>2</sub> Catalysts for CO Oxidation at Low Temperature

Ab initioatomistic thermodynamics study of the early stages of Cu(100) oxidation

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Untitled

Cited by 233 publications

References 12 publications

Complete CO Oxidation over Cu2O Nanoparticles Supported on Silica Gel

Complete CO Oxidation over Cu2O Nanoparticles Supported on Silica Gel

Au/CuO&lt;sub&gt;x&lt;/sub&gt;-TiO&lt;sub&gt;2&lt;/sub&gt; Catalysts for CO Oxidation at Low Temperature

Ab initioatomistic thermodynamics study of the early stages of Cu(100) oxidation

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Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

Complete CO Oxidation over Cu₂O Nanoparticles Supported on Silica Gel

Au/CuO<sub>x</sub>-TiO<sub>2</sub> Catalysts for CO Oxidation at Low Temperature