Electrochemical conversion of oxide spinels into high-entropy alloy

Sure, Jagadeesh; Vishnu, D. Sri Maha; Schwandt, Carsten

doi:10.1016/j.jallcom.2018.10.171

Cited by 31 publications

(12 citation statements)

References 52 publications

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“…For instance, Hu and co-workers proposed a carbothermal shock strategy to prepare HEA NPs by thermally shocking the metal salt mixtures at temperature of ≈2000 K. [134] Similarly, they also reported the high-throughput synthesis of an extensive series of ultrafine multimetallic nanoclusters via thermal shock heating (e.g., ≈1650 K, ≈500 ms). [135] More approaches including fast moving bed pyrolysis, [136] solvothermal, [137] one-pot oil phase synthesis, [138] electrochemical reduction, [139] electro-shock reduction method, [140] and combinatorial co-sputtering [141] have also been reported. Notably, dealloying of bulk HEAs can generate nanoporous HEAs to increase the specific surface area to facilitate catalytic applications.…”

Section: High-entropy Constructionmentioning

confidence: 99%

Multidimensional Nonstoichiometric Electrode Materials for Electrochemical Energy Conversion and Storage

Liu

Jinhan

et al. 2021

Advanced Energy Materials

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number of compounds deviate from definite composite. For example, Wüstite type FeO was found to occur in varied Fe/O ratios with Fe vacancies over a narrow limit in nature, [2,3] while stoichiometric form of FeO was obtained only under high pressure. [4] With the discovery of more chemical compounds with compositions deviating from their stoichiometric counterparts, a new family of materials, which is now recognized as nonstoichiometric material (NMs) or berthollides in honor of Berthollet, has drawn increasing research interest in materials chemistry.Structurally, nonstoichiometry can be induced from defect engineering, element doping, or substitution. [5,6] Although the resulting composition and elemental ratio are allowed to vary in a wide range, the phase and space group of nonstoichiometric compounds are generally identical to the parent stoichiometric counterparts. The type of nonstoichiometry is multidimensional, ranging from point defects (vacancy, substitution or interstitial), local defect (Frenkel pair or cation mixing), linear substitution (typically in layered compounds) to surface defect, bulk composition variation, and spatially dependent concentration gradient. [7] Thermodynamically, deviation from stoichiometry is always accompanied by the change in the system Gibbs free energy and/or redox of characteristic ions, which would endow the materials with multiple physicochemical features in modulating electronic structures, chemical valence, charge storage, carrier diffusion, and stability. [8][9][10][11] Since nonstoichiometry widely exists in many types of compounds including oxides, nitrides, carbides, sulfides, and alloys, it is desirable to develop deep understanding over the fundamental origin, related features, and their contributions to practical functionality.In the context of developing renewable energy conversion and storage, functional electrode materials are crucial to determine the electrochemical performance, stability, and cost. [11,12] In electrocatalysis, exploring highly active electrode materials for hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER) is a key to boost the performance of water splitting, fuel cell, and metalair battery. [13][14][15] Meanwhile, electrochemical nitrogen reduction reaction (NRR) under ambient conditions provides a promising pathway of ammonia synthesis from N 2 and H 2 O alternative to the traditional contaminative Haber-Bosch process. [16] For batteries, the cell voltage, reversible capacity, and cycling Nonstoichiometry plays an important role in determining physicochemical properties such as conductivity, activity, and stability due to the compositioninduced change in phase, local atomic environment, and electronic structure. A variety of materials with nonstoichiometry have emerged in electrochemical energy conversion and storage, which necessitates a solid understanding of their formation mechanism and structure-function relationship. This review presents a summary of the progress made in this ...

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Section: High-entropy Constructionmentioning

confidence: 99%

Multidimensional Nonstoichiometric Electrode Materials for Electrochemical Energy Conversion and Storage

Liu

Jinhan

et al. 2021

Advanced Energy Materials

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“…The versatility of the FFC process has been highlighted in several reviews for the preparation of numerous metals and alloys . A few selected high‐entropy alloys have recently been made in both powder and near‐net‐shape forms . The FFC process has also demonstrated its suitability for the preparation of submicron powders, mainly with a view to Ta for capacitors and for the conversion of otherwise non‐graphitisable carbons into nanostructured graphite .…”

Section: Figurementioning

confidence: 99%

Facile Electrochemical Synthesis of Nanoscale (TiNbTaZrHf)C High‐Entropy Carbide Powder

et al. 2020

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High‐entropy alloys and compounds are becoming an important class of new materials due to their outstanding refractory and high‐temperature properties. However, preparation in bulk quantities and in powder form via classical metallurgical methods is challenging. Here, we report the first synthesis of an ultra‐high‐temperature high‐entropy carbide, (TiNbTaZrHf)C, via a facile electrochemical process. In this, a mixture of the individual metal oxides and graphite is deoxidised in a melt of CaCl2 at a temperature of only 1173 K. The (TiNbTaZrHf)C prepared is single‐phase fcc and has a powdery morphology with a particle‐size range of 15–80 nm. Such materials are in demand for modern additive manufacturing techniques, while preliminary tests have also indicated a possible application in supercapacitors. The successful synthesis of (TiNbTaZrHf)C powder may now guide the way towards establishing the electrochemical route for the preparation of many other entropy‐stabilised materials.

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“…Titanium can be obtained in one-step reduction process [ 13 , 14 ]. At present, the electrochemical method has already been intensely studied in preparation of alloys [ 15 , 16 , 17 , 18 , 19 ] and carbides [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium

Meng

Zhao

et al. 2022

Materials

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Electrochemical mechanisms of molten salt electrolysis from TiO2 to titanium were investigated by Potentiostatic electrolysis, cyclic voltammetry, and square wave voltammetry in NaCl-CaCl2 at 800 °C. The composition and morphology of the product obtained at different electrolysis times were characterized by XRD and SEM. CaTiO3 phase was found in the TiO2 electrochemical reduction process. Electrochemical reduction of TiO2 to titanium is a four-step reduction process, which can be summarized as TiO2→Ti4O7→Ti2O3→TiO→Ti. Spontaneous and electrochemical reactions take place simultaneously in the reduction process. The electrochemical reduction of TiO2→Ti4O7→Ti2O3→TiO affected by diffusion was irreversible.

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Electrochemical conversion of oxide spinels into high-entropy alloy

Cited by 31 publications

References 52 publications

Multidimensional Nonstoichiometric Electrode Materials for Electrochemical Energy Conversion and Storage

Multidimensional Nonstoichiometric Electrode Materials for Electrochemical Energy Conversion and Storage

Facile Electrochemical Synthesis of Nanoscale (TiNbTaZrHf)C High‐Entropy Carbide Powder

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium

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