scholarly journals Subnanometer high-entropy alloy nanowires enable remarkable hydrogen oxidation catalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Changhong Zhan ◽  
Yong Xu ◽  
Lingzheng Bu ◽  
Huaze Zhu ◽  
Yonggang Feng ◽  
...  
Keyword(s):  
Density Functional ◽  
Hydrogen Oxidation ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalysis ◽  
Strong Interactions ◽  
High Entropy Alloy ◽  
Hydrogen Oxidation Reaction ◽  
High Entropy ◽  
Precise Control ◽  
Alloy Nanowires

AbstractHigh-entropy alloys (HEAs) with unique physicochemical properties have attracted tremendous attention in many fields, yet the precise control on dimension and morphology at atomic level remains formidable challenges. Herein, we synthesize unique PtRuNiCoFeMo HEA subnanometer nanowires (SNWs) for alkaline hydrogen oxidation reaction (HOR). The mass and specific activities of HEA SNWs/C reach 6.75 A mgPt+Ru−1 and 8.96 mA cm−2, respectively, which are 2.8/2.6, 4.1/2.4, and 19.8/18.7 times higher than those of HEA NPs/C, commercial PtRu/C and Pt/C, respectively. It can even display enhanced resistance to CO poisoning during HOR in the presence of 1000 ppm CO. Density functional theory calculations reveal that the strong interactions between different metal sites in HEA SNWs can greatly regulate the binding strength of proton and hydroxyl, and therefore enhances the HOR activity. This work not only provides a viable synthetic route for the fabrication of Pt-based HEA subnano/nano materials, but also promotes the fundamental researches on catalysis and beyond.

scholarly journals Publisher Correction: Subnanometer high-entropy alloy nanowires enable remarkable hydrogen oxidation catalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Changhong Zhan ◽  
Yong Xu ◽  
Lingzheng Bu ◽  
Huaze Zhu ◽  
Yonggang Feng ◽  
...  
Keyword(s):  
Hydrogen Oxidation ◽  
Oxidation Catalysis ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Alloy Nanowires

scholarly journals Exploring the Relationship between the CO Oxidation Reaction and the Elemental Composition in Electrocatalysts with Machine Learning - a Case Study of PtRuPdRhAu High Entropy Alloys

2021 ◽  
Author(s):  
Vladislav Mints ◽  
Jack Pedersen ◽  
Alexander Bagger ◽  
Jonathan Quinson ◽  
Andy Anker ◽  
...  
Keyword(s):  
Machine Learning ◽  
Co Oxidation ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Hydrogen Oxidation ◽  
Bayesian Optimization ◽  
High Entropy Alloy ◽  
Onset Potential ◽  
High Entropy ◽  
Co Oxidation Reaction

In recent years, the development of complex multi-metallic nanomaterials like high entropy alloy (HEA) catalysts has gained popularity. Composed of 5 or more metals, the compositions of HEAs exhibit extreme diversity. This is both a promising avenue to identify new catalysts and a severe constraint on their preparation and study. To address the challenges related to the preparation, study and optimization of HEAs, machine learning solutions are attractive. In this paper, the composition of PtRuPdRhAu hydrogen oxidation catalysts is optimized for the CO oxidation reaction. This is achieved by constructing a dataset using Bayesian optimization as guidance. For this quinary nanomaterial, the best performing composition was found within the first 35 experiments. However, the dataset was expanded until a total of 68 samples were investigated. This final dataset was used to construct a random forest regression model and a linear model. These machine learned models were used to assess the relationships between the concentrations of the consituent elements and the CO oxidation reaction onset potential. The onset potentials were found to correlate with the composition dependent adsorption energy of *OH obtained from density functional theory. This study demonstrates, how machine learning can be employed in an experimental setting to investigate the vast compositional space of HEAs.

scholarly journals Multi-cell Monte Carlo method for phase prediction

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Changning Niu ◽  
You Rao ◽  
Wolfgang Windl ◽  
Maryam Ghazisaeidi
Keyword(s):  
Monte Carlo ◽  
Density Functional ◽  
Binary Systems ◽  
Density Functional Theory Calculations ◽  
Monte Carlo Algorithm ◽  
Molar Ratio ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Successful Prediction ◽  
Phase Prediction

AbstractWe propose a Multi-Cell Monte Carlo algorithm, or (MC)$${}^{2}$$2, for predicting stable phases in chemically complex crystalline systems. This algorithm takes advantage of multiple cells to represent possible phases, while eliminating the size and concentration restrictions in the previous counterparts. Free atomic transfer among cells is achieved via the application of the lever rule, where an assigned molar ratio virtually controls the percentage of each cell in the overall simulation, making (MC)$${}^{2}$$2 the first successful algorithm for simulating phase coexistence in crystalline solids. During the application of this method, all energies are directly computed via density functional theory calculations. We test the method by successful prediction of the stable phases of known binary systems. We then apply the method to a quaternary high-entropy alloy. The method is particularly powerful in predicting stable phases of multicomponent systems, for which phase diagrams do not exist.

scholarly journals A First-Principles Study of Hydrogen Desorption from High Entropy Alloy TiZrVMoNb Hydride Surface

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 553
Author(s):  
Jinjing Zhang ◽  
Jutao Hu ◽  
Haiyan Xiao ◽  
Huahai Shen ◽  
Lei Xie ◽  
...  
Keyword(s):  
Density Functional ◽  
Underlying Mechanism ◽  
Hydrogen Desorption ◽  
High Entropy Alloy ◽  
Hydrogen Atoms ◽  
Desorption Process ◽  
High Entropy ◽  
The Density Functional Theory ◽  
Hydride Hydrogen ◽  
Atomic States

The desorption behaviors of hydrogen from high entropy alloy TiZrVMoNb hydride surface have been investigated using the density functional theory. The (110) surface has been determined to be the most preferable surface for hydrogen desorption from TiZrVMoNb hydride. Due to the high lattice distortion and heterogeneous chemical environment in HEA hydride, hydrogen desorption from the HEA hydride surface is found to be complex. A comparison of molecular and atomic hydrogen desorption reveals that hydrogen prefers to desorb in atomic states from TiZrVMoNb hydride (110) surface rather than molecular states during the hydrogen desorption process. To combine as H2 molecules, the hydrogen atoms need to overcome attractive interaction from TiZrVMoNb hydride (110) surface. These results suggest that the hydrogen desorption on TiZrVMoNb hydride (110) surface is a chemical process. The presented results provide fundamental insights into the underlying mechanism for hydrogen desorption from HEA hydride surface and may open up more possibilities for designing HEAs with excellent hydrogen desorption ability.

scholarly journals Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites

2018 ◽  
Vol 115 (48) ◽  
pp. 12124-12129 ◽  
Author(s):  
Benjamin E. R. Snyder ◽  
Max L. Bols ◽  
Hannah M. Rhoda ◽  
Pieter Vanelderen ◽  
Lars H. Böttger ◽  
...  
Keyword(s):  
High Activity ◽  
Active Site ◽  
Active Sites ◽  
High Performance ◽  
Density Functional ◽  
Catalyst Deactivation ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalysis ◽  
Spectroscopic Techniques ◽  
Benzene Hydroxylation

A direct, catalytic conversion of benzene to phenol would have wide-reaching economic impacts. Fe zeolites exhibit a remarkable combination of high activity and selectivity in this conversion, leading to their past implementation at the pilot plant level. There were, however, issues related to catalyst deactivation for this process. Mechanistic insight could resolve these issues, and also provide a blueprint for achieving high performance in selective oxidation catalysis. Recently, we demonstrated that the active site of selective hydrocarbon oxidation in Fe zeolites, named α-O, is an unusually reactive Fe(IV)=O species. Here, we apply advanced spectroscopic techniques to determine that the reaction of this Fe(IV)=O intermediate with benzene in fact regenerates the reduced Fe(II) active site, enabling catalytic turnover. At the same time, a small fraction of Fe(III)-phenolate poisoned active sites form, defining a mechanism for catalyst deactivation. Density-functional theory calculations provide further insight into the experimentally defined mechanism. The extreme reactivity of α-O significantly tunes down (eliminates) the rate-limiting barrier for aromatic hydroxylation, leading to a diffusion-limited reaction coordinate. This favors hydroxylation of the rapidly diffusing benzene substrate over the slowly diffusing (but more reactive) oxygenated product, thereby enhancing selectivity. This defines a mechanism to simultaneously attain high activity (conversion) and selectivity, enabling the efficient oxidative upgrading of inert hydrocarbon substrates.

Rugged High-Entropy Alloy Nanowires with in Situ Formed Surface Spinel Oxide As Highly Stable Electrocatalyst in Zn–Air Batteries

2020 ◽  
Vol 2 (12) ◽  
pp. 1698-1706
Author(s):  
Zeyu Jin ◽  
Juan Lyu ◽  
Yi-Lu Zhao ◽  
Huanglong Li ◽  
Xi Lin ◽  
...  
Keyword(s):  
High Entropy Alloy ◽  
Spinel Oxide ◽  
High Entropy ◽  
Alloy Nanowires

The interplay between structural perfectness and CO oxidation catalysis on aluminum, phosphorous and silicon complexes of corroles

2019 ◽  
Vol 21 (14) ◽  
pp. 7661-7674 ◽  
Author(s):  
Afshan Mohajeri ◽  
Nasim Hassani
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Co Oxidation ◽  
Catalytic Oxidation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalysis ◽  
Functional Theory ◽  
Oxidation Of Carbon Monoxide

Catalytic oxidation of carbon monoxide on perfect and defective structures of corrole complexes with aluminum, phosphorous and silicon have been investigated by performing density functional theory calculations.

Modeling the Electrochemical Hydrogen Oxidation and Evolution Reactions on the Basis of Density Functional Theory Calculations

2010 ◽  
Vol 114 (42) ◽  
pp. 18182-18197 ◽  
Author(s):  
Egill Skúlason ◽  
Vladimir Tripkovic ◽  
Mårten E. Björketun ◽  
Sigrídur Gudmundsdóttir ◽  
Gustav Karlberg ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Oxidation ◽  
Density Functional Theory Calculations ◽  
Functional Theory

Enhanced Catalytic Activity of Carbon Nanotubes for the Oxidation of Cyclohexane by Filling with Fe, Ni, and FeNi alloy Nanowires

2016 ◽  
Vol 69 (6) ◽  
pp. 689 ◽  
Author(s):  
Xixian Yang ◽  
Yuhang Li ◽  
Hao Yu ◽  
Xuchun Gui ◽  
Hongjuan Wang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Wall Thickness ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
General Strategy ◽  
Thin Walls ◽  
Alloy Nanowires ◽  
Relationship Of

Fe-, Ni-, and alloyed FeNi-filled carbon nanotubes (Fe@CNT, Ni@CNT, and FeNi@CNT) were prepared by a general strategy using a mixture of xylene and dichlorobenzene as carbon source, and ferrocene, nickelocene, and their mixture as catalysts. By tailoring the composition of the carbon precursor, the filling ratio and the wall thickness of metal@CNT could be controlled. For the catalytic oxidation of cyclohexane in liquid phase with molecular oxygen as oxidant, the highest activity was obtained over Fe@CNT synthesized from pure dichlorobenzene. However, Ni filling did not improve the activity of CNTs. The effects of metal filling, wall thickness, and defects on catalytic activity were investigated to determine the structure–activity relationship of the filled CNTs. The enhanced catalytic performance can be attributed to a combined contribution of thin walls of CNTs and confined electron-donating metals, which are favourable to electron transfer on the surfaces of CNTs. The modification of the electronic structure of CNTs upon Fe and Ni fillers insertion was elucidated through density functional theory calculations.

scholarly journals Manipulation of Microstructure and Mechanical Properties in N-Doped CoCrFeMnNi High-Entropy Alloys

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1487
Author(s):  
Jing Zhang ◽  
Kook Noh Yoon ◽  
Min Seok Kim ◽  
Heh Sang Ahn ◽  
Ji Young Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Condition ◽  
High Entropy Alloy ◽  
Heterogeneous Structure ◽  
Heterogeneous Microstructure ◽  
New Era ◽  
High Entropy ◽  
Precise Control ◽  
Nitrogen Doped ◽  
Cold Rolling Reduction

Herein, we carefully investigate the effect of nitrogen doping in the equiatomic CoCrFeMnNi high-entropy alloy (HEA) on the microstructure evolution and mechanical properties. After homogenization (1100 °C for 20 h), cold-rolling (reduction ratio of 60%) and subsequent annealing (800 °C for 1 h), a unique complex heterogeneous microstructure consisting of fine recrystallized grains, large non-recrystallized grains, and nanoscale Cr2N precipitates, were obtained in nitrogen-doped (0.3 wt.%) CoCrFeMnNi HEA. The yield strength and ultimate tensile strength can be significantly improved in nitrogen-doped (0.3 wt.%) CoCrFeMnNi HEA with a complex heterogeneous microstructure, which shows more than two times higher than those compared to CoCrFeMnNi HEA under the identical process condition. It is achieved by the simultaneous operation of various strengthening mechanisms from the complex heterogeneous microstructure. Although it still has not solved the problem of ductility reduction, as the strength increases because the microstructure optimization is not yet complete, it is expected that precise control of the unique complex heterogeneous structure in nitrogen-doped CoCrFeMnNi HEA can open a new era in overcoming the strength–ductility trade-off, one of the oldest dilemmas of structural materials.

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