Photoassisted Chemisorption of NO on ZnO

Kase, Kentaro; Yamaguchi, Masataka; Suzuki, Takumi; Kaneko, Katsumi

doi:10.1021/j100036a002

Cited by 7 publications

(5 citation statements)

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“…The illumination of ZnO in the NO atmosphere reduces the electrical conductivity as a result of capture of a d-electron by chemisorbed NO. The capture of a quasi-free electron by a NO molecule is typical for n-type oxides.…”

Section: Resultsmentioning

confidence: 99%

“…A small difference in the areas of lowtemperature (345−360 K) CO adsorption peaks in the dark and in the light is explained by the fact that a significant part of weakly bound CO is desorbed during evacuation before recording the TD spectrum. The illumination of ZnO in the NO atmosphere reduces the electrical conductivity 36 as a result of capture of a d-electron by chemisorbed NO. The capture of a quasi-free electron by a NO molecule is typical for n-type oxides.…”

Section: Experimental Technique and Methodsmentioning

confidence: 99%

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Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

2017

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It is shown for the first time that the photocatalytic reaction of NO reduction by CO into N 2 can occur on selfsensitized ZnO 1−x catalysts upon visible light irradiation (λ > 400 nm) at room temperature with the selectivity reaching 95%. The reaction proceeds in two stages through the intermediate product N 2 O. The formed CO 2 remains on the surface and can be completely desorbed after completion of the photoreaction by heating ZnO 1−x up to 820 K. The spectral dependencies of the first and of the second stages repeat the optical absorption spectra of the ZnO 1−x intrinsic color centers: the oxygen vacancies having captured one or two electrons (F + and F centers), the Zn + ions, and the Zn vacancies having trapped the hole (V − centers). High values of quantum yields in the vis region are caused by large (up to 10 3 s) lifetimes of photoexcited centers.The reaction mechanism is proposed; it includes the following stages: (a) the NO photoadsorption (PA) on the F-type and on V-type centers producing the adsorbed NO − and NO 2 − species, respectively; (b) the reduction of NO − and NO 2 − into N 2 O and further into N 2 by CO which regenerates the donor centers.

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Technique and Methodsmentioning

confidence: 99%

Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

2017

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“…However, Breedon et al have observed a rather weak, although stable, interaction of NO with the (2110) crystal face of ZnO . In other experiments, a photoinduced adsorption of NO on ZnO has been shown, that is, NO physisorbs under dark conditions but attaches strongly when ZnO is photoirradiated . Another example of chemisorbed NO x on a metal oxide surface, and hence unsuitable to form a CT complex, has been recently provided by Kang, who employed the DFT to predict the strong adsorption of NO 2 on MgO (100).…”

Section: Resultsmentioning

confidence: 99%

NO Degradation on the Anatase TiO₂ (001) Surface in the Presence of Water

et al. 2022

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Nitric oxide (NO) is known to degrade to nitric acid (HNO3) on anatase TiO2 facets under visible light irradiation in the presence of water. However, the exact role that water plays in this photoreaction is not fully understood. By employing the density functional theory (DFT) and time-dependent density functional tight binding (TD-DFTB), we show the viability of two suggested degradation pathways involving water. Both reaction pathways are triggered by a charge transfer excitation from the NO molecule to the TiO2 surface. In one of them, NO interacts with dissociated water molecules adsorbed on the surface to form HONO+, whereas for the second pathway, NO is oxidized to NO2 + by capturing one oxygen atom from the substrate. Both HONO and NO2 are known byproducts in the photodegradation of NO, which further react with adsorbed water to finally produce HNO3. We also demonstrate by means of nudged elastic band calculations that these reactions are unlikely to happen without illumination.

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“…The chemisorbed species on the solid surface has been widely studied and almost established methods are available for determination of the different chemisorbed species. For example, representative five species of chemisorbed O 2 , O 2 - , O 2 2- , O - , and O 2- are evident with the aid of IR and ESR for O 2 chemisorbed on the surface of transition metal oxides. , However, interactions in physical adsorption, even micropore filling, are so weak that we have no established method for assignment of the different physisorbed states. The interaction potential profiles of an O 2 molecule with the slit graphite was obtained using Steele's 10−4−3 potential funciton and the Lennard-Jones parameters, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Molecular States of O₂ Confined in a Carbon Nanospace from the Low-Temperature Magnetic Susceptibility

et al. 1997

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The magnetic susceptibility of O2 adsorbed in micropores of activated carbon fibers (ACFs) having different micropore widths was measured at a wide temperature range of 1.7-100 K. The micropore structure of ACF was determined by the analysis of the N2 adsorption isotherm at 77 K. The adsorption isotherm of O2 on ACF at 77 K was determined and it was shown that O2 is adsorbed in the micropore in a similar way to N2 from the Dubinin-Radushkevich analysis of O2 and N2 adsorption isotherms. The -T relation suggested the presence of three kinds of O2 molecular states in the micropore, that is, the isolated, the cluster, and condensed states; their stable region changes with the fractional filling and the temperature. Although the potential energy difference of the O2-surface interaction of different pore systems is only 150 K by the potential calculation, the magnetic susceptibility measurement can sufficiently evidence distinctly the presence of different states of O2 molecules in the micropore.

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Photoassisted Chemisorption of NO on ZnO

Cited by 7 publications

References 0 publications

Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

NO Degradation on the Anatase TiO₂ (001) Surface in the Presence of Water

Molecular States of O₂ Confined in a Carbon Nanospace from the Low-Temperature Magnetic Susceptibility

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Photoassisted Chemisorption of NO on ZnO

Cited by 7 publications

References 0 publications

Photocatalytic Reaction NO + CO + hν → CO2 + 1/2N2 Activated on ZnO1–x in the UV–Vis Region

Photocatalytic Reaction NO + CO + hν → CO2 + 1/2N2 Activated on ZnO1–x in the UV–Vis Region

NO Degradation on the Anatase TiO2 (001) Surface in the Presence of Water

Molecular States of O2 Confined in a Carbon Nanospace from the Low-Temperature Magnetic Susceptibility

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Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

Photocatalytic Reaction NO + CO + hν → CO₂ + 1/2N₂ Activated on ZnO_1–x in the UV–Vis Region

NO Degradation on the Anatase TiO₂ (001) Surface in the Presence of Water

Molecular States of O₂ Confined in a Carbon Nanospace from the Low-Temperature Magnetic Susceptibility