Surface Oxidation and Reduction of CuO and Cu2O Studied Using XPS and XAES

Poulston, Stephen; Parlett, Peter M.; Stone, Peter; Bowker, Michael

doi:10.1002/(sici)1096-9918(199611)24:12<811::aid-sia191>3.0.co;2-z

Cited by 962 publications

(690 citation statements)

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“…The literature reports metallic Cu with a characteristic peak in the range of 918.2 to 918.6 eV; Cu 2 O has a reported peak between 916.0 and 916.4 eV, and the peak for the CuO standard increases from 917.6 to 917.8 eV. [49][50][51][52][53][54][55] The acid-treated Cu sheet resulted in spectra similar to those previously reported in the literature for air-oxidized metallic Cu. 54,55 This oxidized layer was reported to be in the size range of 1.6 to 2.7 nm.…”

Section: Structural Characterizationsupporting

confidence: 77%

“…The XPS spectra of the Cu 2p region are very challenging to interpret because the metallic state of Cu and Cu(I) have statistically similar binding energy values ( Figure S7a). [49][50][51][52][53][54][55] Hence, the X-ray generated Auger spectra were recorded in the Cu L 3 M 45 M 45 region, and the results are presented in Figure 7a. The literature reports metallic Cu with a characteristic peak in the range of 918.2 to 918.6 eV; Cu 2 O has a reported peak between 916.0 and 916.4 eV, and the peak for the CuO standard increases from 917.6 to 917.8 eV.…”

Section: Structural Characterizationmentioning

confidence: 99%

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Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

et al. 2016

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ABSTRACT. We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO 2 to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of −1.0 mA cm −2 at −0.6 V vs. RHE, compared to the CO FE of 63% and −2.1 mA cm −2 for OD-Cu. Excess Sn on the surface caused H 2 evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu-Sn alloy. Auger electron spectroscopy of the sample surface exhibits zero-valent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multi-fold sites on pure Cu, Page 1 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 disfavoring the adsorption of H and leaving the adsorption of CO relatively unperturbed. Our catalytic results along with DFT calculations indicate that the presence of Sn on reduced OD-Cu diminishes the hydrogenation capability-i.e., the selectivity towards H 2 and HCOOH-while hardly affecting the CO productivity. While the pristine monometallic surfaces (both Cu and Sn) fail to selectively reduce CO 2 , the Cu-Sn bimetallic electrocatalyst generates a surface that inhibits adsorbed H*, resulting in improved CO FE. This study presents a strategy to provide a low-cost non-noble metals that can be utilized as a highly selective electrocatalyst for the efficient aqueous reduction of CO 2 . ACS Paragon Plus Environment ACS Catalysis

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Section: Structural Characterizationsupporting

confidence: 77%

Section: Structural Characterizationmentioning

confidence: 99%

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

et al. 2016

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“…A short acquisition time of 10 min was used to examine C 1s, Cu 2p and Cu LMM XPS regions in order to avoid, as much as possible, photoreduction of Cu 2+ species. Nevertheless, a Cu 2+ reduction in high vacuum during the analysis cannot be excluded [49].…”

Section: Characterization Methodsmentioning

confidence: 99%

CuO-CeO2 supported on montmorillonite-derived porous clay heterostructures (PCH) for preferential CO oxidation in H2-rich stream

et al. 2015

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a b s t r a c tThis study reports on the preparation and characterization of porous clay heterostructures (PCH) as a high-surface-area support for CuO-CeO 2 based catalysts for the preferential oxidation of CO in excess of H 2 (CO-PROX). After pillaring the montmorillonite clay with silica (Si-PCH) and silica-zirconia (SiZr-PCH), the Cu-Ce active phase was loaded by incipient wet impregnation setting the cerium amount constant (20 wt%) and investigating three different copper loadings (3, 6 and 12 wt%). The use of pillars of silica or silica-zirconia inserted in the interlayer space of a natural clay provides a high surface area support that can favor the dispersion of both CuO and CeO 2 active phases, leading to the formation of a high amount of copper-ceria interfacial sites, responsible for a very high catalytic activity in the CO-PROX reaction.The results obtained from characterization of the materials by XRD, N 2 physisorption, H 2 -TPR, XPS and CO 2 -TPD suggest that this synthesis method gives rise to catalysts with copper species highly active and selective for the CO-PROX reaction.The catalysts exhibit high CO conversion values and the sample with 6 wt% of copper on Si-PCH displays very good performances, comparable to those based on precious metal catalysts, even at low temperatures.The system reducibility was found modified by the incorporation of zirconium in the support, with a slight decrement of the CO conversion value, compared to the same material without Zr. The influence of the presence of CO 2 and H 2 O in the gas feed was also studied in order to simulate the real operating conditions of a PEMFC feed stream. Correlations between catalytic performances and physicochemical properties of the materials have been made.

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“…Electrochemical CO2 reduction has been well-studied over many decades, 25 and while still far from viable industrial application, improvements in practical and theoretical understanding mean significant progress is still being made towards the technological goal 2 . All of the readily available metals 3 , many metal alloys 4 , oxides 5 and sulphides 6 have been investigated as electrodes for CO2 reduction.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental conditions are described further in the text. treated electrodes show a Cu(II) 2p3/2 peak at 935.3 eV, a Cu(II) 2p1/2 peak at 955.6 eV and well-defined Cu(II) 2p3/2 and 2p1/2 satellite peaks at 944.6 eV and 963.3 eV respectively 25 . The spectrum in both cases is consistent with only CuO being present on the surface.…”

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confidence: 99%

In situ spectroscopic monitoring of CO₂ reduction at copper oxide electrode

et al. 2017

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Copper oxide modified electrodes were investigated as a function of applied electrode potential using in situ infrared spectroscopy and ex situ Raman and X-ray photoelectron spectroscopy. In deoxygenated KHCO3 electrolyte bicarbonate and carbonate species were found to adsorb to the electrode during reduction and the CuO was reduced to Cu(i) or Cu(0) species. Carbonate was incorporated into the structure and the CuO starting material was not regenerated on cycling to positive potentials. In contrast, in CO2 saturated KHCO3 solution, surface adsorption of bicarbonate and carbonate was not observed and adsorption of a carbonato-species was observed with in situ infrared spectroscopy. This species is believed to be activated, bent CO2. On cycling to negative potentials, larger reduction currents were observed in the presence of CO2; however, less of the charge could be attributed to the reduction of CuO. In the presence of CO2 CuO underwent reduction to Cu2O and potentially Cu, with no incorporation of carbonate. Under these conditions the CuO starting material could be regenerated by cycling to positive potentials.

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Surface Oxidation and Reduction of CuO and Cu2O Studied Using XPS and XAES

Cited by 962 publications

References 25 publications

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

CuO-CeO2 supported on montmorillonite-derived porous clay heterostructures (PCH) for preferential CO oxidation in H2-rich stream

In situ spectroscopic monitoring of CO₂ reduction at copper oxide electrode

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Surface Oxidation and Reduction of CuO and Cu2O Studied Using XPS and XAES

Cited by 962 publications

References 25 publications

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO2 to CO

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO2 to CO

CuO-CeO2 supported on montmorillonite-derived porous clay heterostructures (PCH) for preferential CO oxidation in H2-rich stream

In situ spectroscopic monitoring of CO2 reduction at copper oxide electrode

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Product

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Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

In situ spectroscopic monitoring of CO₂ reduction at copper oxide electrode