Experimental and theoretical investigation of the electronic structure of Cu2O and CuO thin films on Cu(110) using x-ray photoelectron and absorption spectroscopy

Peng, Jiang; Prendergast, David; Borondics, Ferenc; Porsgaard, Soeren; Giovanetti, Lisandro J.; Pach, Elzbieta; Newberg, John T.; Bluhm, Hendrik; Besenbacher, Flemming; Salmerón, Miquel

doi:10.1063/1.4773583

Cited by 262 publications

(267 citation statements)

References 67 publications

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“…8). These spectra match well in both peak position and line shape with previously published reports 42,43 . The Cu L-edge spectra of the Cu 2 (OH) 3 Cl precursor at open-circuit potential shows an L 3 -edge peak at 930.7 eV and an L 2 -edge peak at 950.7 eV, which matches well with CuO, clearly indicating that Cu begins in the + 2 oxidation state ( Supplementary Fig.…”

Section: Structural Characterizationsupporting

confidence: 79%

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

et al. 2018

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As energy demand continues to increase, so too do anthropogenic carbon emissions and global temperatures. Renewable energy sources such as solar, wind and hydroelectricity displace fossil fuel carbon emissions and continue to progress to wider deployment. However, long-term (seasonal) energy storage remains a challenge that must be addressed for renewables to meet a major fraction of global energy demand 1 . Carbon dioxide electroreduction to renewable fuels and feedstocks provides an energy storage solution to the seasonal variability of renewable energy sources 2 . When coupled with carbon capture technology, the carbon dioxide reduction reaction (CO 2 RR) offers a means to close the carbon cycle.CO 2 RR electrocatalysts lower energetic barriers to CO 2 reduction by stabilizing intermediates and transition states in the multistep electrochemical reduction process 3 . Copper reduces CO 2 to a wide range of hydrocarbon products such as methane, ethylene, ethanol and propanol 4 . Unfortunately, bulk copper is not selective among various carbon products, and it also suffers Faradaic efficiency (FE) losses to the competing hydrogen evolution reaction.Among possible products, C2+ hydrocarbons are highly sought in view of their commercial value. Ethylene, for example, is a precursor to the production of polyethylene, a major plastic. Selectively producing ethylene over methane circumvents costly paraffin-olefin separation 5 . Developing catalysts that work at ambient conditions to produce C2 selectively over C1 gaseous products will increase the relevance of renewable feedstocks in the chemical sector.Oxide-derived copper is one class of catalyst that has shown enhanced CO 2 RR activity and increased selectivity towards multi-carbon products [6][7][8] . The selectivity of these catalysts is dependent on structural morphology and copper oxidation state 9-17 . Electrochemical reduction of copper oxide catalyst films can lead to grain boundaries, undercoordinated sites and roughened surfaces that are hypothesized to be catalytically active sites 8,18 . Residual oxides, proposed to play a key role in catalysis, may exist after electrochemical reduction 7 . A recent report of oxygen plasma-activated oxide-derived copper catalysts achieved an ethylene FE of 60% at − 0.9 V versus reversible hydrogen electrode (RHE) 9 , with activity attributed to the presence of Cu + species. In situ hard X-ray absorption spectroscopy (hXAS) experiments have suggested stable Cu + species exist at highly negative CO 2 RR potentials of ~− 1.0 versus RHE 9 . However, the presence of Cu + species during CO 2 RR is still the subject of debate; 7,19 and in situ tracking of the copper oxidation state with time resolution during CO 2 RR has remained elusive.Morphological effects of copper nanostructures have a significant effect on the selectivity of CO 2 RR to multi-carbon products [20][21][22][23][24] . Copper catalysts with different morphologies have been synthesized through annealing, chemical treatments on thin films, colloidal synthesis and ...

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Section: Structural Characterizationsupporting

confidence: 79%

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

et al. 2018

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“…Indeed, Young 228 et al and Gwathmey 229 et al found that the order of oxidation rate for the low-index surfaces is (100), (111), (110) with (100) the fastest oxidising facet, for a wide range of temperatures. Rhodin 274 found instead the order to be (100), (110), (111) with (100). This difference in ordering could be due to several factors, for example the use of very different experimental analysis techniques.…”

Section: Long-term Copper Oxidationmentioning

confidence: 99%

“…The MR reconstruction (Fig. 4c, 5b) can be viewed as a c(2 × 2) structure with each fourth [100] row of Cu atoms missing. Between 0.3 and 0.5 ML, Cu atoms are ejected from the c(2 × 2) domains 118,147 and MR islands start forming on terraces, until, at 0.5 ML coverage, a network of missing-row reconstruction islands covers the whole surface 116,133 .…”

Section: Cu(100)mentioning

confidence: 99%

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

Gattinoni

Michaelides

2015

Surface Science Reports

270

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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“…Under an environment of CO and O 2 at elevated pressures, two new peaks develop: one peak at 531.2 eV, which is related to the formation of a small amount of hydroxy groups [15] because of an increase in the amount of background water, and a second peak at 529.1 eV, which is due to the formation of CuO. [16] The TiCuO x film with a submonolayer load of Ti (0.5 AE 0.1 ML) gives only a small CuO peak (529.1 eV), which is likely associated with regions of pure Cu 2 O, compared to the larger peak that was observed for the Cu 2 O film. The presence of titanium preserves the highly active Cu + sites on the surface and thus prevents deactivation of the catalysts.…”

mentioning

confidence: 98%

Stabilization of Catalytically Active Cu⁺ Surface Sites on Titanium–Copper Mixed‐Oxide Films

et al. 2014

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The oxidation of CO is the archetypal heterogeneous catalytic reaction and plays a central role in the advancement of fundamental studies, the control of automobile emissions, and industrial oxidation reactions. Copper-based catalysts were the first catalysts that were reported to enable the oxidation of CO at room temperature, but a lack of stability at the elevated reaction temperatures that are used in automobile catalytic converters, in particular the loss of the most reactive Cu(+) cations, leads to their deactivation. Using a combined experimental and theoretical approach, it is shown how the incorporation of titanium cations in a Cu2O film leads to the formation of a stable mixed-metal oxide with a Cu(+) terminated surface that is highly active for CO oxidation.

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Experimental and theoretical investigation of the electronic structure of Cu2O and CuO thin films on Cu(110) using x-ray photoelectron and absorption spectroscopy

Cited by 262 publications

References 67 publications

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

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

Stabilization of Catalytically Active Cu⁺ Surface Sites on Titanium–Copper Mixed‐Oxide Films

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Experimental and theoretical investigation of the electronic structure of Cu2O and CuO thin films on Cu(110) using x-ray photoelectron and absorption spectroscopy

Cited by 262 publications

References 67 publications

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

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

Stabilization of Catalytically Active Cu+ Surface Sites on Titanium–Copper Mixed‐Oxide Films

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Stabilization of Catalytically Active Cu⁺ Surface Sites on Titanium–Copper Mixed‐Oxide Films