| 1. |
- Eilert, André, et al.
(författare)
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Subsurface Oxygen in Oxide-Derived Copper Electrocatalysts for Carbon Dioxide Reduction
- 2017
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185 .- 1948-7185. ; 8:1, s. 285-290
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Tidskriftsartikel (refereegranskat)abstract
- Copper electrocatalysts derived from an oxide have shown extraordinary electrochemical properties for the carbon dioxide reduction reaction (CO2RR). Using in situ ambient pressure X-ray photoelectron spectroscopy and quasi in situ electron energy loss spectroscopy in a transmission electron microscope, we show that there is a substantial amount of residual oxygen in nanostructured, oxide-derived copper electrocatalysts but no residual copper oxide. On the basis of these findings in combination with density functional theory simulations, we propose that residual subsurface oxygen changes the electronic structure of the catalyst and creates sites with higher carbon monoxide binding energy. If such sites are stable under the strongly reducing conditions found in CO2RR, these findings would explain the high efficiencies of oxide-derived copper in reducing carbon dioxide to multicarbon compounds such as ethylene.
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| 2. |
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| 3. |
- Eriksson, Susanna K., et al.
(författare)
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In-Situ Probing of H2O Effects on a Ru-Complex Adsorbed on TiO2 Using Ambient Pressure Photoelectron Spectroscopy
- 2016
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Ingår i: Topics in catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 59:5-7, s. 583-590
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized interfaces in photocatalytic and solar cells systems are significantly affected by the choice of electrolyte solvent. In the present work, the interface between the hydrophobic Ru-complex Z907, a commonly used dye in molecular solar cells, and TiO2 was investigated with ambient pressure photoelectron spectroscopy (AP-PES) to study the effect of water atmosphere on the chemical and electronic structure of the dye/TiO2 interface. Both laboratory-based Al K alpha as well as synchrotron-based ambient pressure measurements using hard X-ray (AP-HAXPES) were used. AP-HAXPES data were collected at pressures of up to 25 mbar (i.e., the vapor pressure of water at room temperature) showing the presence of an adsorbed water overlayer on the sample surface. Adopting a quantitative AP-HAXPES analysis methodology indicates a stable stoichiometry in the presence of the water atmosphere. However, solvation effects due to the presence of water were observed both in the valence band region and for the S 1s core level and the results were compared with DFT calculations of the dye-water complex.
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| 4. |
- Gustafson, Johan, et al.
(författare)
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The Role of Oxides in Catalytic CO Oxidation over Rhodium and Palladium
- 2018
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 8:5, s. 4438-4445
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Tidskriftsartikel (refereegranskat)abstract
- Catalytic CO oxidation is a seemingly simple reaction between CO and O2 molecules, one of the reactions in automotive catalytic converters, and the fruit-fly reaction in model catalysis. Surprisingly, the phase responsible for the catalytic activity is still under debate, despite decades of investigations. We have performed a simple but yet conclusive study of single crystal Rh and Pd model catalysts, resolving this controversy. For Rh, the oxygen-covered metallic surface is more active than the oxide, while for Pd, thin oxidefilms are at least as active as the metallic surface, but a thicker oxide is less active. Apart from resolving a long-standing debate, our results pinpoint important design principles for oxidation catalysts as to prevent catalytic extinction at high oxygen exposures.
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