Base Alloy Concept in the Development of High-Entropy Materials

Krapivka, М. О.; Myslyvchenko, О. М.; Karpets, M. V.

doi:10.1007/s11106-018-9932-x

Cited by 9 publications

(1 citation statement)

References 20 publications

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“…Mother metal ingots were melted uniformly to obtain a 20 g button ingot of quaternary (Ti, Zr, Nb, and Mo; denoted as 4eHEA), quinary (Cr, Mn, Fe, Co, and Ni; denoted as 5eHEA), or nonary (Ti, Cr, Mn, Fe, Co, Ni, Zr, Nb, and Mo; denoted as 9eHEA) alloys and mechanically sliced into a sheet ( Figure a). X‐ray diffraction (XRD) results show that the crystal structures of 9eHEA could contain a mixture of bcc (4eHEA), fcc (5eHEA), [ 29 ] and new phases, such as C14 and σ phases, which were generated by the introduction of Ti, Zr, Nb, and Mo [ 30 ] (Figure 1b and Table S1, Supporting Information). X‐ray fluorescence (XRF) spectroscopy results show that all HEAs contained different metals at similar molar ratios (Table S2, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Corrosion‐Resistant and High‐Entropic Non‐Noble‐Metal Electrodes for Oxygen Evolution in Acidic Media

et al. 2022

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carrier, in addition to the application of fuel cells operating on hydrogen-rich fuel. Water electrolysis driven by renewable energy is a promising technology [1][2][3] for hydrogen production with zero emission. Water electrolysis can be classified into the following types: alkaline, [4] proton exchange membrane (PEM), [5,6] and anion exchange membrane (AEM). [7,8] Compared to the other types, PEM-type water electrolysis is considered to be more ecofriendly and efficient because it generates no waste, produces highly pure H 2 gas (>99.9999 vol%), [9] and displays a high discharge H 2 pressure (3.0-7.6 MPa) [10] and a high current density (1.0-4.0 A cm −2 ) at low overpotentials (1.5-1.9 V). [3,6,10,11] In contrast, alkaline-and AEM-type water electrolysis produces H 2 with >99.5 vol% and >99.99 vol% purities, respectively. However, efficient electrocatalytic reactions in these systems require considerable amounts of noble metals, for example, 300 kg of Pt in the cathode and 700 kg of Ir in the anode per 1.0 GW of power input of the PEM-type electrolyzer. [11] The serious scarcity of noble metals, especially that of Ir (global production: ≈7 ton year −1 ), [11] To realize a sustainable hydrogen economy, corrosion-resistant non-noblemetal catalysts are needed to replace noble-metal-based catalysts. The combination of passivation elements and catalytically active elements is crucial for simultaneously achieving high corrosion resistance and high catalytic activity. Herein, the self-selection/reconstruction characteristics of multielement (nonary) alloys that can automatically redistribute suitable elements and rearrange surface structures under the target reaction conditions during the oxygen evolution reaction are investigated. The following synergetic effect (i.e., cocktail effect), among the elements Ti, Zr, Nb, and Mo, significantly contributes to passivation, whereas Cr, Co, Ni, Mn, and Fe enhance the catalytic activity. According to the practical water electrolysis experiments, the self-selected/reconstructed multi-element alloy demonstrates high performance under a similar condition with proton exchange membrane (PEM)-type water electrolysis without obvious degradation during stability tests. This verifies the resistance of the alloy to corrosion when used as an electrode under a practical PEM electrolysis condition.

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Section: Resultsmentioning

confidence: 99%

Corrosion‐Resistant and High‐Entropic Non‐Noble‐Metal Electrodes for Oxygen Evolution in Acidic Media

et al. 2022

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Toluene‐Poisoning‐Resistant High‐Entropy Non‐Noble Metal Anode for Direct One‐Step Hydrogenation of Toluene to Methylcyclohexane

Tajuddin,

Ohto,

Tanimoto

et al. 2024

ChemSusChem

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The direct one‐step hydrogenation of toluene to methylcyclohexane facilitated by a proton‐exchange membrane water electrolyzer driven by renewable energy has garnered considerable attention for stable hydrogen storage and safe hydrogen transportation. However, a persistent challenge lies in the crossover of toluene from the cathode to the anode chamber, which deteriorates the anode and decreases its energy efficiency and lifetime. To address this challenge, the catalyst‐poisoning mechanism is systematically investigated using IrO2 and high‐entropic non‐noble‐metal alloys as anodes in acidic electrolytes saturated with toluene and toluene‐oxidized derivatives, such as benzaldehyde, benzyl alcohol, and benzoic acid. Benzoic acid plays an important role in polymer‐like carbon‐film formation by blocking the catalytically active sites on the anode surface. Moreover, Nb and the highly entropic state on the surface of the multi‐element alloy lower the adsorbing ability of toluene and prevent polymer‐like carbon film formation. This study contributes to the design of catalyst‐poisoning‐resistant anodes for organic hydride technology, advanced fuel cells, and batteries.

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Fundamentals of High Entropy Alloys

Nene

2024

High Entropy Alloys

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Base Alloy Concept in the Development of High-Entropy Materials

Cited by 9 publications

References 20 publications

Corrosion‐Resistant and High‐Entropic Non‐Noble‐Metal Electrodes for Oxygen Evolution in Acidic Media

Corrosion‐Resistant and High‐Entropic Non‐Noble‐Metal Electrodes for Oxygen Evolution in Acidic Media

Toluene‐Poisoning‐Resistant High‐Entropy Non‐Noble Metal Anode for Direct One‐Step Hydrogenation of Toluene to Methylcyclohexane

Fundamentals of High Entropy Alloys

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