The Initial Stage in Oxidation of ZrNiSn (Half Heusler) Alloy by Oxygen

TiNiSn-based half-Heusler semiconducting compounds have the highest potential as n-type thermoelectric materials for the use at elevated temperatures. In order to use these compounds in a thermoelectric module, it is crucial to examine their behaviour at a working temperature (approximately 1000 K) under oxygen and a humid atmosphere. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were utilized to study the surface composition and oxidation of the TiNiSn alloy at elevated temperatures. It was found that during heating in vacuum, Sn segregates to the surface. Exposing the alloy to oxygen at room temperature will cause surface oxidation of Ti to TiO2 and Ti2O3 and some minor oxidation of Sn. Oxidation at 1000 K induces Ti segregation to the surface, creating a titanium oxide layer composed of mainly TiO2 as well as Ti2O3 and TiO. Water vapor was found to be a weaker oxidative gas medium compared to oxygen.

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Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

10.26434/chemrxiv.12866588.v1 ◽

2020 ◽

Author(s):

Pablo Lustemberg ◽

Feng Zhang ◽

Ramón A. Gutiérrez ◽

Pedro J. Ramírez ◽

Sanjaya D. Senanayake ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Density Functional ◽

Room Temperature ◽

Elevated Temperatures ◽

Ambient Pressure ◽

Scaling Relations ◽

Time Resolved ◽

X Ray ◽

Metal Support ◽

Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion.

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Photo-Chemical Changes of Aluminium Films on Silicon

MRS Proceedings ◽

10.1557/proc-119-127 ◽

1988 ◽

Vol 119 ◽

Author(s):

A. J. Kellock ◽

J. S. Williams ◽

G. L. Nyberg ◽

J. Liesegang

Keyword(s):

Photoelectron Spectroscopy ◽

Room Temperature ◽

Surface Oxidation ◽

Rutherford Backscattering ◽

Rutherford Backscattering Spectroscopy ◽

Chemical Changes ◽

X Ray ◽

Surface And Interface ◽

Photon Irradiation

AbstractX-ray Photoelectron Spectroscopy and Rutherford Backscattering Spectroscopy with channeling are employed to study surface and interface changes resulting from irradiation of thin Al films on Si-SiO2 substrates using < 6eV visible photons. Results indicati that surface oxidation and bonding rearrangements at the Al-SiO2-Si interface can take place at room temperature under photon bombardment. These changes are correlated with enhanced adhesion and modification of film etch properties which are also a result of photon irradiation.

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Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

10.26434/chemrxiv.12866588 ◽

2020 ◽

Author(s):

Pablo Lustemberg ◽

Feng Zhang ◽

Ramón A. Gutiérrez ◽

Pedro J. Ramírez ◽

Sanjaya D. Senanayake ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Density Functional ◽

Room Temperature ◽

Elevated Temperatures ◽

Ambient Pressure ◽

Scaling Relations ◽

Time Resolved ◽

X Ray ◽

Metal Support ◽

Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion.

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Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

10.26434/chemrxiv.12866588.v2 ◽

2020 ◽

Author(s):

Pablo Lustemberg ◽

Feng Zhang ◽

Ramón A. Gutiérrez ◽

Pedro J. Ramírez ◽

Sanjaya D. Senanayake ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Density Functional ◽

Room Temperature ◽

Elevated Temperatures ◽

Ambient Pressure ◽

Scaling Relations ◽

Time Resolved ◽

X Ray ◽

Metal Support ◽

Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion.

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Initial Oxidation of MBE-Grown Si Surfaces

MRS Proceedings ◽

10.1557/proc-220-35 ◽

1991 ◽

Vol 220 ◽

Author(s):

T. Igarashi ◽

H. Yaguchi ◽

K. Fujita ◽

S. Fukatsu ◽

Y. Shiraki ◽

...

Keyword(s):

Electron Diffraction ◽

Room Temperature ◽

Elevated Temperatures ◽

Surface Oxidation ◽

High Energy ◽

Photoemission Spectroscopy ◽

High Energy Electron ◽

Initial Oxidation ◽

Mbe Growth ◽

X Ray

We investigated the initial oxidation of MBE-grown Si (100) surfaces with atomic flatness using x-ray photoemission spectroscopy (XPS) and reflection high energy electron diffraction (RHEED). It was found that the MBE-grown surfaces are inert and hardly oxidized even after exposure to molecular oxygen up to 1500 Langmuir (L) at room temperature. At elevated temperatures, the surface oxidation was substantially promoted. On the contrary, the surface oxidation was found to be substantiated on a deliberately corrugated Si surface prepared by low temperature MBE growth, even at room temperature.

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Surface oxidation of a quasicrystalline Al–Cu–Fe alloy:No effect of surface orientation and grain boundaries onthe final state

Journal of Materials Research ◽

10.1557/jmr.1999.0427 ◽

1999 ◽

Vol 14 (8) ◽

pp. 3185-3188 ◽

Cited By ~ 19

Author(s):

P. J. Pinhero ◽

J. W. Anderegg ◽

D. J. Sordelet ◽

T. A. Lograsso ◽

D. W. Delaney ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Room Temperature ◽

Surface Oxidation ◽

Surface Orientation ◽

Final State ◽

Random Surface ◽

X Ray ◽

Significant Difference ◽

Single Grain ◽

Effect Of Surface

We have used x-ray photoelectron spectroscopy and Auger electron spectroscopy to examine the characteristics of oxides on two types of quasicrystalline Al–Cu–Fe samples. One type was formed by consolidation of powders, resulting in multiple grains with random surface orientations. The other was a single grain, oriented to expose a fivefold surface. Both were oxidized to saturation in a variety of environments at room temperature. We measured the elemental constituents that oxidized, the extent of oxygen-induced Al segregation, and the depth of the oxide. Under the conditions of our experiments, there was little, if any, significant difference between the two types of samples. Hence, surface orientation and bulk microstructure played little or no role on the final state of the oxide under these conditions.

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Studies of Surface Composition and Phase Transition of Mo-5%Re(1O0)

MRS Proceedings ◽

10.1557/proc-83-29 ◽

1986 ◽

Vol 83 ◽

Cited By ~ 1

Author(s):

G. -C. Wang ◽

D. M. Zehner ◽

H. C. Eaton

Keyword(s):

Phase Transition ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Surface Composition ◽

Structural Phase ◽

Alloy Surface ◽

X Ray ◽

Low Energy Electron Diffraction ◽

Low Energy Electron ◽

Gas Contamination

ABSTRACTSurface composition of a clean Mo-5%Re(100) alloy was determined quantitatively by Auger Electron Spectroscopy and X-Ray Photoelectron Spectroscopy. A slight enrichment of Re on the alloy surface was found at and below room temperatures and the result is consistent with the prediction by a graphical approach for segregation. The change of surface composition due to gas contamination and sputtering were also studied. In contrast to the pure Mo(100) surface where a structural phase transition occurs below room temperature, low energy electron diffraction showed no structural change down to 160 K. However, for H, CO, N chemisorptions and C segregation on the alloy surface, LEED patterns similar to the ones observed from a pure Mo(100) surface were observed.

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Surface Oxidation of Si (111) By High Purity Ozone and Negative Ions Produced by Rydberg Electron Transfer

MRS Proceedings ◽

10.1557/proc-446-53 ◽

1996 ◽

Vol 446 ◽

Author(s):

H. Nonaka ◽

A. Kurokawa ◽

K. Nakamura ◽

S. Ichimura

Keyword(s):

Electron Transfer ◽

High Purity ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Surface Oxidation ◽

Negative Ions ◽

High Flux ◽

Initial Oxidation ◽

X Ray ◽

Rydberg Electron

AbstractThe sub‐initial oxidation of Si (111) surface by a high‐flux pure ozone was investigated using X‐ray photoelectron spectroscopy. In addition to the advantage of the pure ozone which can efficiently oxidize the Si surface at room temperature, the high‐flux ozone was found to further enhance the oxidation. The possibility of producing negative ions of oxidizing gases using Rydberg electron transfer was also investigated.

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CO2 Reduction to Propanol by Copper Foams: A Pre- and Post-Catalysis Study

10.26434/chemrxiv.12022623.v1 ◽

2020 ◽

Author(s):

Jennifer A. Rudd ◽

Ewa Kazimierska ◽

Louise B. Hamdy ◽

Odin Bain ◽

Sunyhik Ahn ◽

...

Keyword(s):

Carbon Dioxide ◽

Photoelectron Spectroscopy ◽

Carbon Capture ◽

Surface Composition ◽

Co2 Reduction ◽

Structural Rearrangement ◽

Copper Electrode ◽

Ex Situ ◽

X Ray ◽

Copper Electrodes

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher value products. Herein, we describe the use of porous copper electrodes to catalyze the reduction of carbon dioxide into higher value products such as ethylene, ethanol and, notably, propanol. For n-propanol production, faradaic efficiencies reach 4.93% at -0.83 V vs RHE, with a geometric partial current density of -1.85 mA/cm2. We have documented the performance of the catalyst in both pristine and urea-modified foams pre- and post-electrolysis. Before electrolysis, the copper electrode consisted of a mixture of cuboctahedra and dendrites. After 35-minute electrolysis, the cuboctahedra and dendrites have undergone structural rearrangement. Changes in the interaction of urea with the catalyst surface have also been observed. These transformations were characterized ex-situ using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. We found that alterations in the morphology, crystallinity, and surface composition of the catalyst led to the deactivation of the copper foams.

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