New model for low-temperature oxidation of copper single crystal

Fujita, Koichi; Ando, Daisuke; Uchikoshi, Masahito; Mimura, Kouji; Isshiki, Minoru

doi:10.1016/j.apsusc.2013.03.096

Cited by 57 publications

(47 citation statements)

References 64 publications

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“…Indeed, it was found that polycrystalline film oxidation kinetics is almost twice as slow as single crystal oxidation kinetics 285 . The oxidation temperature is another factor [288][289][290] . O'Reilly 289 et al found for a polycrystalline sample in dry synthetic air (O 2 /Ar mixture) that at temperatures between 250 and 500 • C the oxidation followed a cubic law, at 100 • C an inverse log rate and at 150 • C a linear growth rate.…”

Section: Long-term Copper Oxidationmentioning

confidence: 99%

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Gattinoni

Michaelides

2015

Surface Science Reports

279

258

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The oxidation and corrosion of metals are fundamental problems in materials science and technology that have been studied using a large variety of experimental and computational techniques. Here we review some of the recent studies that have led to significant advances in our atomic-level understanding of copper oxide, one of the most studied and better understood metal oxides. We show that a good atomistic understanding of the physical characteristics of cuprous (Cu 2 O) and cupric (CuO) oxide and of some key processes of their formation has been obtained. Indeed, the growth of the oxide has been proven to be epitaxial with the surface and to proceed, in most cases, through the formation of oxide nano-islands which, with continuous oxygen exposure, grow and eventually coalesce. We also show how electronic structure calculations have become increasingly useful in helping to characterise the structures and energetics of various Cu oxide surfaces. However a number of challenges remain. For example, it is not clear under which conditions the oxidation of copper in air at room temperature (known as native oxidation) leads to the formation of a cuprous oxide film only, or also of a cupric overlayer. Moreover, the atomistic details of the nucleation of the oxide islands are still unknown. We close our review with a perspective on future work and discuss how recent advances in experimental techniques, bringing greater temporal and spatial resolution, along with improvements in the accuracy, realism and timescales achievable with computational approaches make it possible for these questions to be answered in the near future.

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Section: Long-term Copper Oxidationmentioning

confidence: 99%

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Gattinoni

Michaelides

2015

Surface Science Reports

279

258

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“…[11][12][13] Using ex situ energy-dispersive Xray spectroscopy (EDS), Cuenya and co-workers reported that al arge fraction of the initial oxide can be resistant to reduction even under strongly reducing potentials typically used for CO 2 R. [11,12] They proposed that the presence of Cu + on the surface was important for the formation of C 2 /C 3 products. [19][20][21][22][23] It is therefore possible that OD Cu can rapidly reoxidize,a nd as ar esult the O content characterized ex situ would not be representative of the actual case during CO 2 R.To address these concerns,w ee mployed 18 Oi sotope labeling to confirm the presence/absence of residual oxides in OD Cu during CO 2 R. 18 Oe nriched OD Cu catalysts were synthesized by oxidation/reduction cycling in H 2 18 Ofollowing the procedure of Nilsson and co-workers (see the Supporting Information for full details). [14] First-principles calculations performed by Goddard and co-workers found that the presence of oxygen in the subsurface would generate am ix of Cu + and Cu 0 on the surface.…”

mentioning

confidence: 99%

“…1) Cu nanomaterials have been shown to readily oxidize,which could create difficulties in performing accurate ex situ quantification of the oxygen content; [17,18] 2) Moisture and oxygen are known to cause corrosion (oxidation) of Cu and exposure to both is difficult to avoid;corrosion might also be exacerbated in aporous,high surface area material such as OD Cu;3 )ODC up ossesses ah igh density of grain boundaries,w hich are known to accelerate the oxidation process by serving as nucleation sites and as pathways where diffusion can occur at afaster rate. [19][20][21][22][23] It is therefore possible that OD Cu can rapidly reoxidize,a nd as ar esult the O content characterized ex situ would not be representative of the actual case during CO 2 R.…”

mentioning

confidence: 99%

Stability of Residual Oxides in Oxide‐Derived Copper Catalysts for Electrochemical CO₂ Reduction Investigated with ¹⁸O Labeling

Lum

Ager

2017

Angewandte Chemie

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Oxide-derived (OD) Cu catalysts have high selectivity towards the formation of multi-carbon products (C 2 /C 3 ) for aqueous electrochemical CO 2 reduction (CO 2 R). It has been proposed that al arge fraction of the initial oxide can be surprisingly resistant to reduction, and these residual oxides play acrucial catalytic role.The stability of residual oxides was investigated by synthesizing 18 O-enriched OD Cu catalysts and testing them for CO 2 R. These catalysts maintain ah igh selectivity towardsC 2 /C 3 products (ca. 60 %) for up to 5hin 0.1m KHCO 3 at À1.0 Vv s. RHE. However,s econdary-ion mass spectrometry measurements show that only as mall fraction (< 1%)o ft he original 18 Oc ontent remains,s howing that residual oxides are not present in significant amounts during CO 2 R. Furthermore,weshow that OD Cu can reoxidize rapidly,w hichc ould compromise the accuracy of ex situ methods for determining the true oxygen content.Electrochemical reduction of CO 2 (CO 2 R) into chemical fuels and feedstock, powered by renewable electrical energy, has been proposed as astrategy to mitigate rising greenhouse gas emissions. [1][2][3] Twomain challenges in this area of research are improving the product selectivity and reducing the overpotentials required to drive CO 2 R. [2,4,5] Oxide-derived Cu (OD Cu) catalysts have attracted much attention because they exhibit higher selectivity towards potentially valuable multi-carbon products (for example,e thanol and ethylene) with lower overpotential requirements. [6][7][8][9][10][11][12][13] OD Cu catalysts are formed by oxidizing Cu and subsequently reducing it. Recently,i th as been proposed that residual oxides are responsible for its remarkable catalytic properties. [11][12][13] Using ex situ energy-dispersive Xray spectroscopy (EDS), Cuenya and co-workers reported that al arge fraction of the initial oxide can be resistant to reduction even under strongly reducing potentials typically used for CO 2 R. [11,12] They proposed that the presence of Cu + on the surface was important for the formation of C 2 /C 3 products. [12] Nilsson and co-workers studied an OD Cu catalyst with ambient pressure X-ray photoelectron spectroscopy (XPS) and electron energy-loss spectroscopy (EELS) and they found as mall amount of oxygen residing in the subsurface,possibly modifying the electronic structure of the catalyst and creating active sites with higher CO binding energy. [14] First-principles calculations performed by Goddard and co-workers found that the presence of oxygen in the subsurface would generate am ix of Cu + and Cu 0 on the surface. These could then work with adsorbed H 2 Oa nd aid in CO 2 activation by forming chemisorbed CO 2 ,which is the first step of CO 2 R. [15] In aseparate report, they investigated apartially reduced copper oxide matrix consisting of am ix of Cu 0 and Cu + regions. [16] They showed that Cu + and Cu 0 regions could act synergistically to promote CO dimerization and suppress C 1 pathways,t hereby boosting catalyst selectivity.However,afew aspects of this ...

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“…Recently, a detailed study of oxidation mechanism of the formation of Cu 2 O on copper surface was reported by Fujita et al [34]. For typical partial pressure of oxygen of 1.01 kPa, the formation of a 2 nm layer requires *10 ks at 60°C.…”

Section: Resultsmentioning

confidence: 97%

High quality oxide-free metallic nanoparticles: a strategy for synthesis through laser ablation in aqueous medium

Malviya

Chattopadhyay

2014

J Mater Sci

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The paper explores the synthesis of oxide-free nanoparticles of Ag and Cu through laser ablation of pure targets under aqueous medium and tuning the quality and size through addition of Polyvinylpyrrolidone (PVP) in the medium. The size distribution of nanoparticles reduces from 37 ± 30 nm and 13 ± 5 nm to 32 ± 12 nm and 4 ± 1 nm for Ag and Cu with changes in PVP concentration from 0.00 to 0.02 M, respectively. Irregular shaped particles of Ag with Ag 2 O phase and a Cu-Cu 2 O coreshell particles form without the addition of PVP, while oxide layer is absent with 0.02 M of PVP. The recent understanding of the mechanism of particle formation during laser ablation under liquid medium allows us to rationalize our observation.

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New model for low-temperature oxidation of copper single crystal

Cited by 57 publications

References 64 publications

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Stability of Residual Oxides in Oxide‐Derived Copper Catalysts for Electrochemical CO₂ Reduction Investigated with ¹⁸O Labeling

High quality oxide-free metallic nanoparticles: a strategy for synthesis through laser ablation in aqueous medium

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New model for low-temperature oxidation of copper single crystal

Cited by 57 publications

References 64 publications

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Stability of Residual Oxides in Oxide‐Derived Copper Catalysts for Electrochemical CO2 Reduction Investigated with 18O Labeling

High quality oxide-free metallic nanoparticles: a strategy for synthesis through laser ablation in aqueous medium

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Stability of Residual Oxides in Oxide‐Derived Copper Catalysts for Electrochemical CO₂ Reduction Investigated with ¹⁸O Labeling