Scholarlink

<p><b>Abstract</b>—The electrochemical behavior of lanthanum ions and their joint electroreduction with nickel ions on a tungsten electrode in a KCl–NaCl–CsCl eutectic melt at 823 K are studied using cyclic and square-wave voltammetry and open-circuit chronopotentiometry. The electroreduction of La<sup>3+</sup> ions proceeds reversibly in one three-electron step up to polarization rates of 0.1 V/s. An increase in the polarization rate makes it possible to reveal the slowness of the charge-transfer step and transition to a quasi-reversible character of the charge transfer. For a combined presence of lanthanum and nickel ions in the KCl–NaCl–CsCl eutectic melt, the reduction wave of nickel ions at the potentials from –0.12 to –0.3 V and that of lanthanum ions at the potentials from –2.13 to –2.18 V relative to the silver chloride reference electrode are observed on the voltammograms. In addition to these waves, the voltammograms contain three reduction waves at the potentials from –1.68 to –1.77, from –1.95 to –2.0, and from –2.13 to –2.18 V. These waves appear due to the joint electroreduction of lanthanum and nickel ions on metallic nickel preliminarily separated on the tungsten electrode with a certain depolarization and to the formation of intermetallic phases of lanthanum and nickel of various compositions La<sub><i>x</i></sub>Ni<sub><i>y</i></sub>. The voltage–time (<i>E</i>–<i>t</i>) dependences of open-circuit chronopotentiometry reveal a plateau of potential delay corresponding to the dissolution of individual phases of lanthanum and nickel intermetallic compounds. Based on the results of voltammetry measurements and open-circuit chronopotentiometry, a series of electrochemical syntheses are carried out in the potentiostatic mode at the potentials from –1.7 to –2.1 V. At a certain ratio of lanthanum and nickel chloride concentrations in the KCl–NaCl–CsCl eutectic melt and a temperature of 823 K, intermetallic phases LaNi<sub>5</sub>, La<sub>2</sub>Ni<sub>7</sub>, LaNi<sub>3</sub>, La<sub>2</sub>Ni<sub>3</sub>, and LaNi<sub>2</sub> are formed. The synthesized samples of lanthanum and nickel intermetallic compounds are characterized by phase X-ray diffraction (XRD) analysis.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Mechanism of the Joint Electroreduction of La3+ and Ni2+ Ions in a KCl–NaCl–CsCl Eutectic Melt at 823 K

  • 期刊论文

  • 发表日期：

    2025年2月1日

查看全文
  • Kh. B. Kushkhov,
  • F. A. Kisheva,
  • Z. A. Zhanikaeva

摘要

Abstract—The electrochemical behavior of lanthanum ions and their joint electroreduction with nickel ions on a tungsten electrode in a KCl–NaCl–CsCl eutectic melt at 823 K are studied using cyclic and square-wave voltammetry and open-circuit chronopotentiometry. The electroreduction of La3+ ions proceeds reversibly in one three-electron step up to polarization rates of 0.1 V/s. An increase in the polarization rate makes it possible to reveal the slowness of the charge-transfer step and transition to a quasi-reversible character of the charge transfer. For a combined presence of lanthanum and nickel ions in the KCl–NaCl–CsCl eutectic melt, the reduction wave of nickel ions at the potentials from –0.12 to –0.3 V and that of lanthanum ions at the potentials from –2.13 to –2.18 V relative to the silver chloride reference electrode are observed on the voltammograms. In addition to these waves, the voltammograms contain three reduction waves at the potentials from –1.68 to –1.77, from –1.95 to –2.0, and from –2.13 to –2.18 V. These waves appear due to the joint electroreduction of lanthanum and nickel ions on metallic nickel preliminarily separated on the tungsten electrode with a certain depolarization and to the formation of intermetallic phases of lanthanum and nickel of various compositions LaxNiy. The voltage–time (E–t) dependences of open-circuit chronopotentiometry reveal a plateau of potential delay corresponding to the dissolution of individual phases of lanthanum and nickel intermetallic compounds. Based on the results of voltammetry measurements and open-circuit chronopotentiometry, a series of electrochemical syntheses are carried out in the potentiostatic mode at the potentials from –1.7 to –2.1 V. At a certain ratio of lanthanum and nickel chloride concentrations in the KCl–NaCl–CsCl eutectic melt and a temperature of 823 K, intermetallic phases LaNi5, La2Ni7, LaNi3, La2Ni3, and LaNi2 are formed. The synthesized samples of lanthanum and nickel intermetallic compounds are characterized by phase X-ray diffraction (XRD) analysis.