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

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. <br>

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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. <br>

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High-Pressure Structural Behavior and Equation of State of Kagome Staircase Compound, Ni3V2O8

Crystals ◽

10.3390/cryst10100910 ◽

2020 ◽

Vol 10 (10) ◽

pp. 910

Author(s):

Daniel Diaz-Anichtchenko ◽

Robin Turnbull ◽

Enrico Bandiello ◽

Simone Anzellini ◽

Daniel Errandonea

Keyword(s):

High Pressure ◽

Equation Of State ◽

Density Functional ◽

Room Temperature ◽

Ambient Pressure ◽

Density Functional Theory Calculations ◽

X Ray Diffraction ◽

X Ray ◽

Cell Parameters ◽

A Chain

We report on high-pressure synchrotron X-ray diffraction measurements on Ni3V2O8 at room-temperature up to 23 GPa. According to this study, the ambient-pressure orthorhombic structure remains stable up to the highest pressure reached in the experiments. We have also obtained the pressure dependence of the unit-cell parameters, which reveals an anisotropic compression behavior. In addition, a room-temperature pressure–volume third-order Birch–Murnaghan equation of state has been obtained with parameters: V0 = 555.7(2) Å3, K0 = 139(3) GPa, and K0′ = 4.4(3). According to this result, Ni3V2O8 is the least compressible kagome-type vanadate. The changes of the crystal structure under compression have been related to the presence of a chain of edge-sharing NiO6 octahedral units forming kagome staircases interconnected by VO4 rigid tetrahedral units. The reported results are discussed in comparison with high-pressure X-ray diffraction results from isostructural Zn3V2O8 and density-functional theory calculations on several isostructural vanadates.

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In situ investigation of water on MXene interfaces

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2108325118 ◽

2021 ◽

Vol 118 (49) ◽

pp. e2108325118

Author(s):

Wahid Zaman ◽

Ray A. Matsumoto ◽

Matthew W. Thompson ◽

Yu-Hsuan Liu ◽

Yousuf Bootwala ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Water Adsorption ◽

Elevated Temperatures ◽

Ambient Pressure ◽

Transition Metal Carbide ◽

Water Removal ◽

Water Mobility ◽

Level Control ◽

X Ray ◽

In Situ Investigation

A continuum of water populations can exist in nanoscale layered materials, which impacts transport phenomena relevant for separation, adsorption, and charge storage processes. Quantification and direct interrogation of water structure and organization are important in order to design materials with molecular-level control for emerging energy and water applications. Through combining molecular simulations with ambient-pressure X-ray photoelectron spectroscopy, X-ray diffraction, and diffuse reflectance infrared Fourier transform spectroscopy, we directly probe hydration mechanisms at confined and nonconfined regions in nanolayered transition-metal carbide materials. Hydrophobic (K+) cations decrease water mobility within the confined interlayer and accelerate water removal at nonconfined surfaces. Hydrophilic cations (Li+) increase water mobility within the confined interlayer and decrease water-removal rates at nonconfined surfaces. Solutes, rather than the surface terminating groups, are shown to be more impactful on the kinetics of water adsorption and desorption. Calculations from grand canonical molecular dynamics demonstrate that hydrophilic cations (Li+) actively aid in water adsorption at MXene interfaces. In contrast, hydrophobic cations (K+) weakly interact with water, leading to higher degrees of water ordering (orientation) and faster removal at elevated temperatures.

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Ambient Pressure X-ray Photoelectron Spectroscopy Study of Room-Temperature Oxygen Adsorption on Cu(100) and Cu(111)

Applied Surface Science ◽

10.1016/j.apsusc.2022.152438 ◽

2022 ◽

pp. 152438

Author(s):

Bo-Hong Liu ◽

Maximilian Huber ◽

Matthijs A. van Spronsen ◽

Miquel Salmeron ◽

Hendrik Bluhm

Keyword(s):

Photoelectron Spectroscopy ◽

Room Temperature ◽

Ambient Pressure ◽

Oxygen Adsorption ◽

Spectroscopy Study ◽

X Ray

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Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

Nanomaterials ◽

10.3390/nano10020323 ◽

2020 ◽

Vol 10 (2) ◽

pp. 323 ◽

Cited By ~ 3

Author(s):

Ludovico Macera ◽

Giuliana Taglieri ◽

Valeria Daniele ◽

Maurizio Passacantando ◽

Franco D’Orazio

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Magnetic Measurements ◽

Ambient Pressure ◽

Synthesis Method ◽

Hematite Nanoparticles ◽

X Ray

This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2/g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2/g, which is among the highest values reported in the literature for hematite NPs.

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