scholarly journals Deciphering atomistic mechanisms of the gas-solid interfacial reaction during alloy oxidation

2020 ◽  
Vol 6 (17) ◽  
pp. eaay8491
Author(s):  
Langli Luo ◽  
Liang Li ◽  
Daniel K. Schreiber ◽  
Yang He ◽  
Donald R. Baer ◽  
...  
Keyword(s):  
Interfacial Reaction ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Surface Oxidation ◽  
Atomic Scale ◽  
Al Alloy ◽  
Initial Surface ◽  
Ion Diffusion ◽  
Alloy Oxidation ◽  
Interfacial Strain

Gas-solid interfacial reaction is critical to many technological applications from heterogeneous catalysis to stress corrosion cracking. A prominent question that remains unclear is how gas and solid interact beyond chemisorption to form a stable interphase for bridging subsequent gas-solid reactions. Here, we report real-time atomic-scale observations of Ni-Al alloy oxidation reaction from initial surface adsorption to interfacial reaction into the bulk. We found distinct atomistic mechanisms for oxide growth in O2 and H2O vapor, featuring a “step-edge” mechanism with severe interfacial strain in O2, and a “subsurface” one in H2O. Ab initio density functional theory simulations rationalize the H2O dissociation to favor the formation of a disordered oxide, which promotes ion diffusion to the oxide-metal interface and leads to an eased interfacial strain, therefore enhancing inward oxidation. Our findings depict a complete pathway for the Ni-Al surface oxidation reaction and delineate the delicate coupling of chemomechanical effect on gas-solid interactions.

scholarly journals Oxygen adsorption on (100) surfaces in Fe–Cr alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matti Ropo ◽  
Marko Punkkinen ◽  
Pekko Kuopanportti ◽  
Muhammad Yasir ◽  
Sari Granroth ◽  
...  
Keyword(s):  
Density Functional ◽  
Oxygen Affinity ◽  
Surface Oxidation ◽  
Oxygen Adsorption ◽  
Adsorption Site ◽  
Atomic Scale ◽  
Comprehensive Understanding ◽  
Surface Layers ◽  
Subsurface Layers ◽  
Theoretical Results

AbstractThe adsorption of oxygen on bcc Fe–Cr(100) surfaces with two different alloy concentrations is studied using ab initio density functional calculations. Atomic-scale analysis of oxygen–surface interactions is indispensable for obtaining a comprehensive understanding of macroscopic surface oxidation processes. Up to two chromium atoms are inserted into the first two surface layers. Atomic geometries, energies and electronic properties are investigated. A hollow site is found to be the preferred adsorption site over bridge and on-top sites. Chromium atoms in the surface and subsurface layers are found to significantly affect the adsorption properties of neighbouring iron atoms. Seventy-one different adsorption geometries are studied, and the corresponding adsorption energies are calculated. Estimates for the main diffusion barriers from the hollow adsorption site are given. Whether the change in the oxygen affinity of iron atoms can be related to the chromium-induced charge transfer between the surface atoms is discussed. The possibility to utilize the presented theoretical results in related experimental research and in developing semiclassical potentials for simulating the oxidation of Fe–Cr alloys is addressed.

scholarly journals InP and AlInP(001)(2 × 4) Surface Oxidation from Density Functional Theory

ACS Omega ◽  
2021 ◽  
Author(s):  
Isaac Azahel Ruiz Alvarado ◽  
Marsel Karmo ◽  
Erich Runge ◽  
Wolf Gero Schmidt
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Surface Oxidation ◽  
Functional Theory

scholarly journals Dynamics of Oxidation of Reduced Forms of CO2 under Electrochemical and Open-Сircuit Conditions on Polycrystalline Pt in H2CO3

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 274
Author(s):  
Alexander V. Smolin ◽  
Мikhail N. Mikhailov ◽  
Aleksey F. Gadzaov ◽  
Leonid M. Kustov
Keyword(s):  
Quantum Chemical ◽  
Preliminary Analysis ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Oxidation Process ◽  
Open Circuit ◽  
Organic Substances ◽  
Oxidation Of Co ◽  
Reduced Forms

The problem of identifying correlations between catalytic and electrocatalytic processes is one of the fundamental problems of catalysis among “simple” organic substances, and the oxidation of CO and rCO2 is of great interest, since CO and CO2 are considered in pairs both during catalytic and electrocatalytic transformations. In the case of electrocatalysis, this analysis is important in the study of fuel cells. In this paper, we studied the correlation between the oxidation of reduced forms of CO2 (rCO2) under potentiodynamic-galvanoctatic electrochemical and open-circuit conditions of measurements on polycrystalline (pc)Pt in H2CO3. Periodic oscillations are revealed at the oxidation of Had and rCO2 on (pc)Pt. Quantum chemical calculations were carried out on the Pt13 cluster in order to identify the mechanisms of the rCO2 oxidation reaction. The correspondence in the energy parameters of the oxidation process of rCO2 under open-circuit conditions and electrochemical conditions is shown. The preliminary analysis of the system using density functional (DFT) calculations is carried out and the most stable systems that are based on Pt13 are found, namely rOH-Pt13-(CO)n, rOH-Pt13-(COH) and rOH-Pt13-(rCOOH). OH• species was chosen as the most likely candidate for the role of the oxidant for rCO2. Preliminary calculations for the expected reactions were carried out, and the optimal PES is revealed.

A dynamic reaction density functional theory for interfacial reaction-diffusion coupling at nanoscale

2021 ◽  
Vol 236 ◽  
pp. 116513 ◽  
Author(s):  
Weiqiang Tang ◽  
Hongping Yu ◽  
Teng Zhao ◽  
Leying Qing ◽  
Xiaofei Xu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Interfacial Reaction ◽  
Density Functional ◽  
Reaction Diffusion ◽  
Dynamic Reaction ◽  
Functional Theory ◽  
Diffusion Coupling

scholarly journals Na-ion diffusion in a NASICON-type solid electrolyte: a density functional study

2016 ◽  
Vol 18 (39) ◽  
pp. 27226-27231 ◽  
Author(s):  
Kieu My Bui ◽  
Van An Dinh ◽  
Susumu Okada ◽  
Takahisa Ohno
Keyword(s):  
Density Functional Theory ◽  
Solid Electrolyte ◽  
Electronic Structures ◽  
Density Functional ◽  
Diffusion Mechanism ◽  
Functional Study ◽  
Ion Diffusion ◽  
Functional Theory ◽  
Density Functional Study ◽  
Nasicon Type

Based on density functional theory, we have systematically studied the crystal and electronic structures, and the diffusion mechanism of the NASICON-type solid electrolyte Na3Zr2Si2PO12.

scholarly journals Designing order–disorder transformation in high-entropy ferritic steels

2021 ◽  
Author(s):  
Prashant Singh ◽  
Duane D. Johnson
Keyword(s):  
Short Range ◽  
Density Functional ◽  
Short Range Order ◽  
Range Order ◽  
Atomic Scale ◽  
Atomic Fraction ◽  
Compositional Variation ◽  
Ferritic Steels ◽  
Chemical Inhomogeneity ◽  
High Entropy

AbstractOrder–disorder transformations hold an essential place in chemically complex high-entropy ferritic steels (HEFSs) due to their critical technological application. The chemical inhomogeneity arising from mixing of multi-principal elements of varying chemistry can drive property altering changes at the atomic scale, in particular short-range order. Using density-functional theory-based linear-response theory, we predict the effect of compositional tuning on the order–disorder transformation in ferritic steels—focusing on Cr–Ni–Al–Ti–Fe HEFSs. We show that Ti content in Cr–Ni–Al–Ti–Fe solid solutions can be tuned to modify short-range order that changes the order–disorder path from BCC-B2 (Ti atomic-fraction = 0) to BCC-B2-L21 (Ti atomic-fraction > 0) consistent with existing experiments. Our study suggests that tuning degree of SRO through compositional variation can be used as an effective means to optimize phase selection in technologically useful alloys. Graphic abstract

scholarly journals DFT Studies of Graphene-Functionalised Derivatives of Capecitabine

2017 ◽  
Vol 72 (12) ◽  
pp. 1131-1138 ◽  
Author(s):  
Mehdi Aramideh ◽  
Mahmoud Mirzaei ◽  
Ghadamali Khodarahmi ◽  
Oğuz Gülseren
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Atomic Scale ◽  
Phase System ◽  
Molecular Models ◽  
Functional Theory ◽  
Atomic Properties ◽  
Scale Properties ◽  
Derivatives Of

AbstractCancer is one of the major problems for so many people around the world; therefore, dedicating efforts to explore efficient therapeutic methodologies is very important for researchers of life sciences. In this case, nanostructures are expected to be carriers of medicinal compounds for targeted drug design and delivery purposes. Within this work, the graphene (Gr)-functionalised derivatives of capecitabine (CAP), as a representative anticancer, have been studied based on density functional theory calculations. Two different sizes of Gr molecular models have been used for the functionalisation of CAP counterparts, CAP-Gr3 and CAP-Gr5, to explore the effects of Gr-functionalisation on the original properties of CAP. All singular and functionalised molecular models have been optimised and the molecular and atomic scale properties have been evaluated for the optimised structures. Higher formation favourability has been obtained for CAP-Gr5 in comparison with CAP-Gr3 and better structural stability has been obtained in the water-solvated system than the isolated gas-phase system for all models. The CAP-Gr5 model could play a better role of electron transferring in comparison with the CAP-Gr3 model. As a concluding remark, the molecular properties of CAP changed from singular to functionalised models whereas the atomic properties remained almost unchanged, which is expected for a carrier not to use significant perturbations to the original properties of the carried counterpart.

scholarly journals Density functional study on the CO oxidation reaction mechanism on MnN2-doped graphene

RSC Advances ◽  
2020 ◽  
Vol 10 (46) ◽  
pp. 27856-27863
Author(s):  
Mingming Luo ◽  
Zhao Liang ◽  
Chao Liu ◽  
Xiaopeng Qi ◽  
Mingwei Chen ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Co Oxidation ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study ◽  
Co Oxidation Reaction ◽  
Doped Graphene ◽  
First Time

The various COOR mechanisms on MnN2-doped graphene (MnN2C2: MnN2C2-hex, MnN2C2-opp, MnN2C2-pen) were investigated for the first time.

scholarly journals Atomic-Scale Mechanism Investigation of Mass Transfer in Laser Fabrication Process of Ti-Al Alloy via Molecular Dynamics Simulation

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1660
Author(s):  
Ziqi Cui ◽  
Xianglin Zhou ◽  
Qingbo Meng
Keyword(s):  
Molecular Dynamics ◽  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Particle System ◽  
Fabrication Process ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Al Alloy ◽  
Laser Fabrication ◽  
Solute Atoms

This article deals with a Ti-Al alloy system. Molecular dynamics simulation was used to simulate and explore the mass transfer behavior during the laser fabrication process at atomic scale. The research goal is to investigate the mass transfer mechanism at atomic scale and the movement of solute atoms during the laser fabrication process. The mean square displacement (MSD), radial distribution function (RDF), atomic number density, and atomic displacement vector were calculated to characterize it. The results show that the TiAl alloy is completely melted when heated up to 2400 K, and increasing the temperature past 2400 K has little effect on mass transfer. As the heating time increases, the diffusion coefficient gradually decreases, the diffusion weakens, and the mass transfer process gradually stabilizes. In Ti-Al binary alloys, the diffusion coefficients of different solute atoms are related to the atomic fraction. During the melting process, the alloy particle system has a greater diffusion coefficient than the elemental particle system.

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