Surface Chemistry of Carbon Dioxide on Copper Model Catalysts Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy

Koitaya, Takanori; Yamamoto, Susumu; Matsuda, Ichiro; Yoshinobu, Jun

doi:10.1380/ejssnt.2019.169

Cited by 13 publications

(7 citation statements)

References 85 publications

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“…On the CuO x /Cu(111) region of the surface without zirconia (lower spectra, Figure ), the peaks associated with surface intermediates are substantially smaller and shifted in energy relative to the C(ad) peak in the corresponding spectra with zirconia on the surface. For example, the fitted data reveal a peak at ∼285.6 eV which falls between the H x CO* and CH 3 O* features in the spectra in the zirconia region; since this peak exhibits similar intensity trends as H x CO* and CH 3 O* in the zirconia region, we assign this peak at ∼285.6 eV to H x C–O* and H x CO species, consistent with other reported values for these species on bare Cu surfaces. , The peak at ∼287.7 eV is assigned to formate (HCOO*) based on previous studies of CO 2 exposure on Cu and CuO x /Cu(111) surfaces, although it may also overlap contributions from carboxylate (CO 2 δ− ). ,,,, Consequently, we label this peak as CO 2 δ− /HCOO*. At even higher binding energy (289.7–289.9 eV), a small peak appears between 400 and 500 K and is tentatively assigned to carbonate (*CO 3 ). ,,− Overall, the carbon-based species observed in the surface region without zirconia are consistent with CO 2 interactions on Cu and CuO x surfaces and are clearly distinguishable from those in the Zr/CuO 2 /Cu(111) surface region.…”

Section: Resultssupporting

confidence: 87%

“…97,98 The peak at ∼287.7 eV is assigned to formate (HCOO*) based on previous studies of CO 2 exposure on Cu and CuO x /Cu(111) surfaces, although it may also overlap contributions from carboxylate (CO 2 δ− ). 76,90,93,98,99 Consequently, we label this peak as CO 2 δ− /HCOO*. At even higher binding energy (289.7− 289.9 eV), a small peak appears between 400 and 500 K and is tentatively assigned to carbonate (*CO 3 ).…”

Section: Identification Of Surface Species By Irasmentioning

confidence: 99%

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Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Wang

Goodman

et al. 2020

J. Phys. Chem. C

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Copper−zirconia catalysts have been shown to be effective for methanol synthesis via CO 2 hydrogenation, yet the active phases and reaction mechanism remain uncertain. In this work, an inverse model catalyst ZrO 2 /CuO 2 /Cu(111) was prepared by massselected ion deposition and tested for CO 2 hydrogenation under nearambient pressure (AP) reaction conditions by using X-ray photoelectron spectroscopy (NAP-XPS) and infrared reflection−absorption spectroscopy (NAP-IRAS). The spatial resolution afforded by the small entrance cone of the AP-XPS spectrometer was used to resolve regions of the surface with and without Zr deposition. Carbon 1s core level spectra of the ZrO 2 /Cu 2 O/Cu(111) regions of the surface under 500 mTorr of CO 2 + H 2 (1:3 ratio) show evidence for reaction intermediates including carbonate (CO 3 *), formate (HCOO*), and H x CO* species, with methoxy having the highest surface concentration at 500−600 K. These intermediates are confirmed by IRAS vibrational spectra. In regions of the surface without Zr, the Cu 2 O/Cu( 111) is reduced to metallic Cu, and the surface intermediates are different and are present at much lower concentrations. The observed surface intermediates and their temperature dependence suggest a mechanism in which CO 2 is adsorbed on zirconia as carbonate (CO 3 *) and then converted to HCOO* and H x CO* hydrogenated intermediates that ultimately lead to methoxy (CH 3 O*), the final surface-bound precursor for methanol. Overall, the results clearly demonstrate the promotional effects of small ZrO 2 particles for enhancing the reactivity of Cu surfaces for CO 2 hydrogenation.

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Section: Resultssupporting

confidence: 87%

Section: Identification Of Surface Species By Irasmentioning

confidence: 99%

Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Wang

Goodman

et al. 2020

J. Phys. Chem. C

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“…The experiments were performed at the AP-XPS endstation , at SPring-8 BL07LSU . The photon energy and flux of incident X-rays were 735 eV and 1.2 × 10 15 s –1 cm –2 , respectively.…”

Section: Methodsmentioning

confidence: 99%

Band Bending of n-GaN under Ambient H₂O Vapor Studied by X-ray Photoelectron Spectroscopy

et al. 2021

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To improve the performance of semiconductor photoelectrodes for water splitting, the amount of band bending in the depletion layer of a semiconductor should be accurately ascertained, since it determines the splitting efficiency of photogenerated carriers. Band bending has been determined by X-ray photoelectron spectroscopy (XPS) from the valence band maximum (VBM), which has been calculated from the Ga 3d peak using the energy difference between VBM and Ga 3d (ΔE VBM‑3d). This work validates several values for ΔE VBM‑3d which have been reported previously, by analyzing the spectrum around the VBM and its distance from Ga 3d for the n-GaN(0001) surface under both ultrahigh vacuum (UHV) and ambient H2O. ΔE VBM‑3d is estimated to be between 17.36 and 17.55 eV. By adopting 17.5 eV as ΔE VBM‑3d, the amounts of band-bending were 0.5 eV under UHV and 0.1 eV under a relative humidity of 46%, respectively. For the latter condition, a surface photovoltage of 20 meV was observed upon Xe lamp irradiation, confirming the existence of band bending even with H2O adsorption on the surface. The origin of such band bending seems to be Fermi level pinning to the subsurface states which cannot be compensated by H2O.

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“…The XPS spectra were obtained with a photon energy of 735 eV and photon flux of 1.1 × 10 15 s –1 cm –2 . The details of this endstation can be found in refs and . The samples (Ga-polar n-GaN grown on the Si substrate by metal organic chemical vapor phase epitaxy, thickness of n-GaN of 2.5 μm) used in this study, were purchased from Nuflare Technology.…”

Section: Computational and Experimental Methodologymentioning

confidence: 99%

Atomistic-Level Description of GaN/Water Interface by a Combined Spectroscopic and First-Principles Computational Approach

et al. 2020

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Photocatalytic water splitting takes place at the semiconductor/electrolyte interface. Although the reactions are strongly affected by the subtle changes in the interface structure, little is known about the interface from an atomistic point of view. In this study, we investigate the GaN(0001)/water interface structure by combining first-principles calculation and ambient pressure X-ray photoelectron spectroscopy (AP-XPS). In particular, the relationship between the geometric and electronic structure of the interface is revealed. First, the evolution of the GaN/water interface structure upon water adsorption is predicted from firstprinciples calculations. Computational results indicate that (1) at low coverage (below 3/4 monolayer), the Fermi level is pinned to the surface states originating from surface Ga atom dangling bonds, and water adsorbs dissociatively, forming oxygen atoms as well as hydroxyl groups, and (2) at higher coverage (above 3/4 monolayer), the Fermi level becomes free from the pinning, and adsorption of intact water becomes dominant. AP-XPS measurements were carried out for the water coverage ranging from submonolayer (low coverage) to several monolayers (high coverage). The core-level binding energies calculated from first-principles were used successfully to assign the adsorbate species to experimental O 1s peaks. Both the electronic and geometric structures predicted by the first-principles calculation explain well the experimental spectra obtained by the AP-XPS measurements. The results demonstrate that the combined spectroscopic and first-principles computational approach offers a detailed atomic level understanding of the solid/liquid interface structures.

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Surface Chemistry of Carbon Dioxide on Copper Model Catalysts Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy

Cited by 13 publications

References 85 publications

Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Band Bending of n-GaN under Ambient H₂O Vapor Studied by X-ray Photoelectron Spectroscopy

Atomistic-Level Description of GaN/Water Interface by a Combined Spectroscopic and First-Principles Computational Approach

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Surface Chemistry of Carbon Dioxide on Copper Model Catalysts Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy

Cited by 13 publications

References 85 publications

Reactivity of a Zirconia–Copper Inverse Catalyst for CO2 Hydrogenation

Reactivity of a Zirconia–Copper Inverse Catalyst for CO2 Hydrogenation

Band Bending of n-GaN under Ambient H2O Vapor Studied by X-ray Photoelectron Spectroscopy

Atomistic-Level Description of GaN/Water Interface by a Combined Spectroscopic and First-Principles Computational Approach

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Product

Resources

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Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Reactivity of a Zirconia–Copper Inverse Catalyst for CO₂ Hydrogenation

Band Bending of n-GaN under Ambient H₂O Vapor Studied by X-ray Photoelectron Spectroscopy