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Göthelid, Mats
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Publications (10 of 12) Show all publications
Marks, K., Besharat, Z., Soldemo, M., Önsten, A., Weissenrieder, J., Stenlid, J. H., . . . Göthelid, M. (2019). Adsorption and Decomposition of Ethanol on Cu2O(111) and (100). JOURNAL OF PHYSICAL CHEMISTRY C, 123(33), 20384-20392
Open this publication in new window or tab >>Adsorption and Decomposition of Ethanol on Cu2O(111) and (100)
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2019 (English)In: JOURNAL OF PHYSICAL CHEMISTRY C, Vol. 123, no 33, p. 20384-20392Article in journal (Refereed) Published
Abstract [en]

Ethanol dehydrogenation on metal oxides such as Cu2O is an important reaction for the production of renewable energy by fuel cells both via the production of H-2 fuel and via application in direct alcohol fuel cells. To better understand this reaction, we studied the adsorption, dissociation, and desorption of ethanol on Cu2O(111) and (100) surfaces using high-resolution photoelectron spectroscopy, vibrational sum-frequency generation spectroscopy, and temperature-programmed desorption accompanied by density functional theory calculations. On Cu-2(100), the first layer consists primarily of dissociatively adsorbed ethoxy. Second and third layers of ethanol physisorb at low temperatures and desorb below 200 K. On the Cu2O(111) surface, adsorption is mixed as ethoxy, ethanol, and the products following C-C cleavage, CHx, and OCHx, are found in the first layer. Upon heating, products following both C-C and C-O bond breaking are observed on both surfaces and continued heating accentuates molecular cracking. C-O cleavage occurs more on the (100) surface, whereas on the Cu2O(111) surface, C-C cleavage dominates and occurs at lower temperatures than those for the (100) surface. The increased ability of Cu2O(111) to crack ethanol is explained by the varied surface structure including surface oxygen, electron-rich O vacancies, and Cu.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-259447 (URN)10.1021/acs.jpcc.9b05394 (DOI)000482545700035 ()2-s2.0-85071416412 (Scopus ID)
Note

QC 20190923

Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-09-23Bibliographically approved
Kanerva, M., Besharat, Z., Pärnänen, T., Jokinen, J., Honkanen, M., Sarlin, E., . . . Schlenzka, D. (2019). Automatization and stress analysis data of CoCr laser weld fatigue tests. Data in Brief, 26, Article ID 104374.
Open this publication in new window or tab >>Automatization and stress analysis data of CoCr laser weld fatigue tests
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2019 (English)In: Data in Brief, E-ISSN 2352-3409, Vol. 26, article id 104374Article in journal (Refereed) Published
Abstract [en]

This work includes raw and analyzed test data when using a recently developed fatigue test method for miniature laser welds in cobalt-chromium (CoCr) alloy joints [1]: 10.1016/j.jmbbm.2019.07.004. The automization of fatigue tests is crucial for saving costs and personnel resources and that is the reason why the atomization threshold and the resulting spectrum data related to CoCr welds are provided here. The finite element method based stress computation output is provided related to shearing-mode tests to support the dataset as a whole. In addition, the compositional data of the parent material and the laser weld are given.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Automatization, CoCr, Fatigue, Laser, Testing, Welding
National Category
Medical Materials
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-263545 (URN)10.1016/j.dib.2019.104374 (DOI)000495079400012 ()2-s2.0-85072173471 (Scopus ID)
Note

QC 20191128

Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2019-12-19Bibliographically approved
Paulraj, A. R., Kiros, Y., Chamoun, M., Svengren, H., Noréus, D., Göthelid, M., . . . Johansson, M. B. (2019). Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes. Batteries (1)
Open this publication in new window or tab >>Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes
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2019 (English)In: Batteries, E-ISSN 2313-0105, no 1Article in journal (Other academic) Published
Abstract [en]

Fe-air or Ni-Fe cells can offer low-cost and large-scale sustainable energy storage. At present, they are limited by low coulombic efficiency, low active material use, and poor rate capability. To overcome these challenges, two types of nanostructured doped iron materials were investigated: (1) copper and tin doped iron (CuSn); and (2) tin doped iron (Sn). Single-wall carbon nanotube (SWCNT) was added to the electrode and LiOH to the electrolyte. In the 2 wt. % Cu + 2 wt. % Sn sample, the addition of SWCNT increased the discharge capacity from 430 to 475 mAh g−1, and charge efficiency increased from 83% to 93.5%. With the addition of both SWCNT and LiOH, the charge efficiency and discharge capacity improved to 91% and 603 mAh g−1, respectively. Meanwhile, the 4 wt. % Sn substituted sample performance is not on par with the 2 wt. % Cu + 2 wt. % Sn sample. The dopant elements (Cu and Sn) and additives (SWCNT and LiOH) have a major impact on the electrode performance. To understand the relation between hydrogen evolution and charge current density, we have used in operando charging measurements combined with mass spectrometry to quantify the evolved hydrogen. The electrodes that were subjected to prolonged overcharge upon hydrogen evolution failed rapidly. This insight could help in the development of better charging schemes for the iron electrodes.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Iron electrodes, Cu and Sn-doped iron, SWCNT and LiOH additives, charge efficiency, hydrogen evolution, GC-MS analysis
National Category
Chemical Process Engineering
Research subject
Chemistry; Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-241278 (URN)10.3390/batteries5010001 (DOI)000464125800001 ()2-s2.0-85068355323 (Scopus ID)
Note

QC 20190121

Available from: 2019-01-17 Created: 2019-01-17 Last updated: 2019-10-04Bibliographically approved
Marks, K., Ghadami Yazdi, M., Piskorz, W., Simonov, K., Stefanuik, R., Sostina, D., . . . Ostrom, H. (2019). Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111). Journal of Chemical Physics, 150(24), Article ID 244704.
Open this publication in new window or tab >>Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111)
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2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 24, article id 244704Article in journal (Refereed) Published
Abstract [en]

The temperature dependent dehydrogenation of naphthalene on Ni(111) has been investigated using vibrational sum-frequency generation spectroscopy, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory with the aim of discerning the reaction mechanism and the intermediates on the surface. At 110 K, multiple layers of naphthalene adsorb on Ni(111); the first layer is a flat lying chemisorbed monolayer, whereas the next layer(s) consist of physisorbed naphthalene. The aromaticity of the carbon rings in the first layer is reduced due to bonding to the surface Ni-atoms. Heating at 200 K causes desorption of the multilayers. At 360 K, the chemisorbed naphthalene monolayer starts dehydrogenating and the geometry of the molecules changes as the dehydrogenated carbon atoms coordinate to the nickel surface; thus, the molecule tilts with respect to the surface, recovering some of its original aromaticity. This effect peaks at 400 K and coincides with hydrogen desorption. Increasing the temperature leads to further dehydrogenation and production of H-2 gas, as well as the formation of carbidic and graphitic surface carbon. 

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-255435 (URN)10.1063/1.5098533 (DOI)000473303200040 ()31255092 (PubMedID)2-s2.0-85068220749 (Scopus ID)
Note

QC 20190820

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-08-20Bibliographically approved
Kanerva, M., Besharat, Z., Parnanen, T., Jokinen, J., Honkanen, M., Sarlin, E., . . . Schlenzka, D. (2019). Miniature CoCr laser welds under cyclic shear: Fatigue evolution and crack growth. Journal of The Mechanical Behavior of Biomedical Materials, 99, 93-103
Open this publication in new window or tab >>Miniature CoCr laser welds under cyclic shear: Fatigue evolution and crack growth
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2019 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 99, p. 93-103Article in journal (Refereed) Published
Abstract [en]

Miniature laser welds with the root depth in the range of 50-300 pm represent air-tight joints between the components in medical devices, such as those in implants, growth rods, stents and various prostheses. The current work focuses on the development of a fatigue test specimen and procedure to determine fatigue lives of shear-loaded laser welds. A cobalt-chromium (CoCr) alloy is used as a benchmark case. S-N graphs, damage process, and fracture surfaces are studied by applying x-ray analysis, atomic force microscopy, and scanning electron microscopy both before and after the crack onset. A non-linear material model is fitted for the CoCr alloy to run finite element simulations of the damage and deformation. As a result, two tensile-loaded specimen designs are established and the performance is compared to that of a traditional torque-loaded specimen. The new generation specimens show less variation in the determined fatigue lives due to well-defined crack onset point and, therefore, precise weld seam load during the experiments. The fatigue damage concentrates to the welded material and the entire weld experiences fatigue prior to the final, fracture-governed failure phase. For the studied weld seams of hardened CoCr, a regression fatigue limit of 10.8-11.8 MPa, where the stress refers to the arithmetic average shear stress computed along the region dominated by shear loading, is determined.

Place, publisher, year, edition, pages
ELSEVIER, 2019
Keywords
CoCr, Implant, Fatigue, Crack growth, Laser weld
National Category
Materials Engineering
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-260988 (URN)10.1016/j.jmbbm.2019.07.004 (DOI)000484871500010 ()31349149 (PubMedID)2-s2.0-85069732362 (Scopus ID)
Note

QC 20191010

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-11-26Bibliographically approved
Ghadami Yazdi, M., Lousada, C. M., Evertsson, J., Rullik, L., Soldemo, M., Bertram, F., . . . Göthelid, M. (2019). Structure dependent effect of silicon on the oxidation of Al(111) and Al(100). Surface Science, 684, 1-11
Open this publication in new window or tab >>Structure dependent effect of silicon on the oxidation of Al(111) and Al(100)
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2019 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 684, p. 1-11Article in journal (Refereed) Published
Abstract [en]

The effect of sub-monolayer silicon on the oxidation of Al(111) and Al(100) surfaces was investigated using X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. On both surfaces the adatom site is preferred over substituting Si into the Al-lattice; on Al(100) the four fold hollow site is vastly favored whereas on Al(111) bridge and hollow sites are almost equal in energy. Upon O 2 exposure, Si is not oxidized but buried at the metal/oxide interface under the growing aluminum oxide. On Al(111), Si has a catalytic effect on both the initial oxidation by aiding in creating a higher local oxygen coverage in the early stages of oxidation and, in particular, at higher oxide coverages by facilitating lifting Al from the metal into the oxide. The final oxide, as measured from the Al2p intensity, is 25–30% thicker with Si than without. This observation is valid for both 0.1 monolayer (ML) and 0.3 ML Si coverage. On Al(100), on the other hand, at 0.16 ML Si coverage, the initial oxidation is faster than for the bare surface due to Si island edges being active in the oxide growth. At 0.5 ML Si coverage the oxidation is slower, as the islands coalesce and he amount of edges reduces. Upon oxide formation the effect of Si vanishes as it is overgrown by Al 2 O 3 , and the oxide thickness is only 6% higher than on bare Al(100), for both Si coverages studied. Our findings indicate that, in addition to a vanishing oxygen adsorption energy and Mott potential, a detailed picture of atom exchange and transport at the metal/oxide interface has to be taken into account to explain the limiting oxide thickness.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Aluminum, Density functional theory, Oxidation, Silicon, X-ray photoelectron spectroscopy
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-246413 (URN)10.1016/j.susc.2019.02.005 (DOI)000470192900001 ()2-s2.0-85061563000 (Scopus ID)
Note

QC 20190402

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-06-25Bibliographically approved
Suvanam, S. S., Usman, M., Martin, D., Yazdi, M. G., Linnarsson, M. K., Tempez, A., . . . Hallén, A. (2018). Improved interface and electrical properties of atomic layer deposited Al2O3/4H-SiC. Applied Surface Science, 433, 108-115
Open this publication in new window or tab >>Improved interface and electrical properties of atomic layer deposited Al2O3/4H-SiC
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 433, p. 108-115Article in journal (Refereed) Published
Abstract [en]

In this paper we demonstrate a process optimization of atomic layer deposited Al2O3 on 4H-SiC resulting in an improved interface and electrical properties. For this purpose the samples have been treated with two pre deposition surface cleaning processes, namely CP1 and CP2. The former is a typical surface cleaning procedure used in SiC processing while the latter have an additional weak RCA1 cleaning step. In addition to the cleaning and deposition, the effects of post dielectric annealing (PDA) at various temperatures in N2O ambient have been investigated. Analyses by scanning electron microscopy show the presence of structural defects on the Al2O3 surface after annealing at 500 and 800 °C. These defects disappear after annealing at 1100 °C, possibly due to densification of the Al2O3 film. Interface analyses have been performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight medium energy ion scattering (ToF MEIS). Both these measurements show the formation of an interfacial SiOx (0 < x < 2) layer for both the CP1 and CP2, displaying an increased thickness for higher temperatures. Furthermore, the quality of the sub-oxide interfacial layer was found to depend on the pre deposition cleaning. In conclusion, an improved interface with better electrical properties is shown for the CP2 sample annealed at 1100 °C, resulting in lower oxide charges, strongly reduced flatband voltage and leakage current, as well as higher breakdown voltage.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
4H-SiC, Al2O3, High-K dielectric, Interface trap densities, Annealing, Atomic layer deposition, Cleaning, Deposition, Optimization, Scanning electron microscopy, Silicon carbide, Surface cleaning, Surface defects, Atomic layer deposited, Interface analysis, Interface trap density, Medium energy ion scattering, Structural defect, Surface cleaning procedure, X ray photoelectron spectroscopy
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-223127 (URN)10.1016/j.apsusc.2017.10.006 (DOI)000418883800014 ()2-s2.0-85031746823 (Scopus ID)
Funder
Swedish Research Council, D0674701
Note

QC 20180327

Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-04-11Bibliographically approved
Paulraj, A. R., Kiros, Y., Göthelid, M. & Johansson, M. B. (2018). NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media. catalyst, 8(8)
Open this publication in new window or tab >>NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media
2018 (English)In: catalyst, Vol. 8, no 8Article in journal (Refereed) Published
Abstract [en]

This article reports the two-step synthesis of NiFeOx nanomaterials and their characterization and bifunctional electrocatalytic activity measurements in alkaline electrolyte for metal-air batteries. The samples were mostly in layered double hydroxide at the initial temperature, but upon heat treatment, they were converted to NiFe2O4 phases. The electrochemical behaviour of the different samples was studied by linear sweep voltammetry and cyclic voltammetry on the glassy carbon electrode. The OER catalyst activity was observed for low mass loadings (0.125 mg cm−2), whereas high catalyst loading exhibited the best performance on the ORR side. The sample heat-treated at 250 °C delivered the highest bi-functional oxygen evolution and reduction reaction activity (OER/ORR) thanks to its thin-holey nanosheet-like structure with higher nickel oxidation state at 250 °C. This work further helps to develop low-cost electrocatalyst development for metal-air batteries

National Category
Other Chemical Engineering Chemical Process Engineering
Research subject
Chemical Engineering; Chemistry
Identifiers
urn:nbn:se:kth:diva-241281 (URN)10.3390/catal8080328 (DOI)000442517100033 ()2-s2.0-85052506473 (Scopus ID)
Funder
Swedish Energy Agency, 39078-01
Note

QC 20190124

Available from: 2019-01-17 Created: 2019-01-17 Last updated: 2019-08-20Bibliographically approved
Besharat, Z., Ghadami Yazdi, M., Wakeham, D., Johnson, M., Rutland, M. W., Göthelid, M. & Grönbeck, H. (2018). Se-C Cleavage of Hexane Selenol at Steps on Au(111). Langmuir, 34(8), 2630-2636
Open this publication in new window or tab >>Se-C Cleavage of Hexane Selenol at Steps on Au(111)
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2018 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, no 8, p. 2630-2636Article in journal (Refereed) Published
Abstract [en]

Selenols are considered as an alternative to thiols in self-assembled monolayers, but the Se-C bond is one limiting factor for their usefulness. In this study, we address the stability of the Se-C bond by a combined experimental and theoretical investigation of gas phase-deposited hexane selenol (CH3(CH2)(5)SeH) on Au(111) using photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory (DFT). Experimentally, we find that initial adsorption leaves atomic Se on the surface without any carbon left on the surface, whereas further adsorption generates a saturated selenolate layer. The Se 3d component from atomic Se appears at 0.85 eV lower binding energy than the selenolate-related component. DFT calculations show that the most stable structure of selenols on Au(111) is in the form of RSe-Au-SeR complexes adsorbed on the unreconstructed Au(111) surface. This is similar to thiols on Au(111). Calculated Se 3d core-level shifts between elemental Se and selenolate in this structure nicely reproduce the experimentally recorded shifts. Dissociation of RSeH and subsequent formation of RH are found to proceed with high barriers on defect-free Au(111) terraces, with the highest barrier for scissoring R-Se. However, at steps, these barriers are considerably lower, allowing for Se-C bond breaking and hexane desorption, leaving elemental Se at the surface. Hexane is the selenol to selenolate formed by replacing the Se-C bond with a H-C bond by using the hydrogen liberated from transformation.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
Ray Photoelectron-Spectroscopy, Resolution Photoemission-Spectroscopy, Core-Level Shifts, Assembled Monolayers, Gold Surfaces, Mono Layers, Adsorption, Thiol, Alkanethiols, Stability
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-225082 (URN)10.1021/acs.langmuir.7b03713 (DOI)000426614100006 ()29405715 (PubMedID)2-s2.0-85042636157 (Scopus ID)
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research
Note

QC 20180328

Available from: 2018-03-28 Created: 2018-03-28 Last updated: 2018-03-28Bibliographically approved
Besharat, Z., Halldin Stenlid, J., Soldemo, M., Marks, K., Önsten, A., Johnson, M., . . . Göthelid, M. (2017). Dehydrogenation of methanol on Cu2O(100) and (111). Journal of Chemical Physics, 146(24)
Open this publication in new window or tab >>Dehydrogenation of methanol on Cu2O(100) and (111)
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2017 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 24Article in journal (Refereed) Published
Abstract [en]

Adsorption and desorption of methanol on the (111) and (100) surfaces of  Cu2O have been studied using high-resolution photoelectron spectroscopy in the temperature range 120–620 K, in combination with density functional theorycalculations and sum frequency generation spectroscopy. The bare (100) surfaceexhibits a (3,0; 1,1) reconstruction but restructures during the adsorption process into a Cu-dimer geometry stabilized by methoxy and hydrogen binding in Cu-bridge sites. During the restructuring process, oxygen atoms from the bulk that can host hydrogen appear on the surface. Heating transforms methoxy to formaldehyde, but further dehydrogenation is limited by the stability of the surface and the limited access to surface oxygen. The (√3 × √3)R30°-reconstructed (111) surface is based on ordered surface oxygen and copper ions and vacancies, which offers a palette of adsorption and reaction sites. Already at 140 K, a mixed layer of methoxy, formaldehyde, and CHxOy is formed. Heating to room temperature leaves OCH and CHx. Thus both CH-bond breaking and CO-scission are active on this  surface at low temperature. The higher ability to dehydrogenate methanol on (111) compared to (100) is explained by the multitude of adsorption sites and, in particular, the availability of surfaceoxygen.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-211786 (URN)10.1063/1.4989472 (DOI)000404302600033 ()2-s2.0-85021446807 (Scopus ID)
Note

QC 20170816

Available from: 2017-08-13 Created: 2017-08-13 Last updated: 2017-11-10Bibliographically approved
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