Technetium electrochemistry at the turn of the century

Kuznetsov, V. V.; Chotkowski, Maciej; Poineau, Frédéric; Volkov, Mikhail A.; German, K. É.; Филатова, Е. В.

doi:10.1016/j.jelechem.2021.115284

Cited by 9 publications

(3 citation statements)

References 111 publications

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“…The HER in a 0.5 M solution of H 2 SO 4 on the Tc x C−C cathode is strongly hindered compared to that of metallic technetium (Figure 7). 35 Such an inhibition cannot be explained only by a simple decrease in the atomic fraction of technetium on the electrode surface. One can conclude that the phase of technetium carbide has a higher overpotential of hydrogen evolution compared to that of metallic technetium.…”

Section: Synthesis Of Hexamethyleneiminium Pertechnetate (Compound Ii...mentioning

confidence: 99%

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Kuznetsov,

German,

Nagovitsyna

et al. 2023

Inorg. Chem.

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Technetium–carbon nanophases are obtained by thermal decomposition of pertechnetates with large organic cations under an argon atmosphere. Parallel carbonization of organic cations (hexamethyleneiminium and triphenylguanidinium), which occurs during the thermal decomposition of their pertechnetates, leads to the formation of X-ray amorphous solid products. An X-ray absorption fine structure study revealed that they have a crystal structure containing technetium–carbon bonds with a length of 1.76 Å. After subsequent annealing treatment at 1073–1673 K, the synthesized technetium–carbon phase has a cubic lattice with an a of 4.01 ± 0.03 Å. The products of thermal decomposition of the same perrhenates are also X-ray amorphous; however, unlike that of pertechnetates, the distance between rhenium and carbon atoms in them is significantly greater (2.14 Å). After subsequent annealing, they have a hexagonal lattice. The electrochemical properties of technetium–carbon nanophases prepared by thermal decomposition of pertechnetates with large organic cations are different from the properties of those prepared with metallic technetium. The oxidation of technetium carbide to its oxides at the electrode surface observed in the first anodic scan of cyclic voltammograms can be used for the deposition of noble metal nanoclusters under open-circuit conditions to prepare composite catalysts for the hydrogen evolution reaction. Nanotechnetium in the amorphous carbon matrix can also be a prospective material for reactor transmutation of technetium to stable isotopically pure ruthenium-100.

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Section: Synthesis Of Hexamethyleneiminium Pertechnetate (Compound Ii...mentioning

confidence: 99%

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Kuznetsov,

German,

Nagovitsyna

et al. 2023

Inorg. Chem.

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“…Carboxylates of Mn(II), Mn(III), and Mn(IV) have been previously reported. − Based on manganese carboxylates, framework-type structures were obtained . Previously, carboxylate systems of Tc(VII) compounds were considered as electrolytes for metallic technetium coatings. − The literature states that the electroreduction mechanism of pertechnetate anions results in the creation of Tc(IV) compounds. ,, However, isolating individual compounds and determining their structure were not studied. Polymer-chain cluster complexes of Tc 2 (OOCCH 3 ) 5 were previously reported as obtained from Tc(VII) compounds .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Technetium Carboxylates: Wheel-Like Octanuclear Clusters (Tc₈(μ-O)₈(RCOO)₁₆, Where R = CF₃, C₆H₅)─Potential Nanobuilding Units for Tc-MOFs

Volkov,

Abkhalimov,

Novikov

et al. 2024

Inorg. Chem.

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Herein, we studied the behavior of TcO4 – in trifluoroacetic anhydride (TFAA) under visible light irradiation in situ by UV–vis spectroscopy. One carboxylate of Tc(VII) C2F3O5Tc (1) and two wheel-like carboxylate clusters of Tc(IV) Tc8(μ-O)8(CF3COO)16 (2, 3) and Tc8(μ-O)8(C6H5COO)16 (4) were synthesized and analyzed using pXRD, TGA, UV–vis spectroscopy, and SCXRD techniques. According to SCXRD, it was found that Tc(IV) trifluoroacetate exists in two crystalline modifications. By UV–vis spectroscopy and DFT calculations, it was shown that the primary compound in the reaction system is trifluoroacetate Tc(VII). A technetium trifluoroacetate(VII) and Tc intermediates of unidentified nature both show photosensitivity. The influence of intermolecular noncovalent interactions on the volatility of trifluoroacetate and benzoate Tc(IV) is shown. The main regularities of chemical transformations of technetium in nonaqueous solutions of carboxylates have been revealed. The obtained data on the kinetics of the process suggest that technetium in trifluoroacetic anhydride can simultaneously exist in the form of Tc(VII), Tc(VI), Tc(V), and Tc(IV). Under laser ionization or prolonged heating, the formation of the Tc(II,III)-cluster is observed.

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“…Despite the clear relevance of the reduction of Tc(VII) from an environmental and chemical point of view, more than 80 years after the discovery of technetium, its reduction mechanisms in water are not well understood yet . Although several studies have been performed, especially in acidic media, − it is not clear whether it proceeds in a direct three-electron transfer or if there are intermediary oxidation states involved. − Moreover, there is no systematic study of the effect of pH and ionic strength on the mechanism. There are also some contradictions observed in the literature.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach

et al. 2022

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Technetium (Tc) is an environmentally relevant radioactive contaminant whose migration is limited when Tc(VII) is reduced to Tc(IV). However, its reaction mechanisms are not well understood yet. We have combined electrochemistry, spectroscopy, and microscopy (cyclic voltammetry, rotating disk electrode, X-ray photoelectron spectroscopy, and Raman and scanning electron microscopy) to study Tc(VII) reduction in noncomplexing media: 0.5 mM KTcO 4 in 2 M NaClO 4 in the pH from 2.0 to 10.0. At pH 2.0, Tc(VII) first gains 2.3 ± 0.3 electrons, following Tc(V) rapidly receives 1.3 ± 0.3 electrons yielding Tc(IV). At pH 4.0−10.0, Tc(IV) is directly obtained by transfer of 3.2 ± 0.3 electrons. The reduction of Tc(VII) produced always a black solid identified as Tc(IV) by Raman and XPS. Our results narrow a significant gap in the fundamental knowledge of Tc aqueous chemistry and are important to understand Tc speciation. They provide basic steps on the way from non-complexing to complex media.

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Technetium electrochemistry at the turn of the century

Cited by 9 publications

References 111 publications

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Synthesis of Technetium Carboxylates: Wheel-Like Octanuclear Clusters (Tc₈(μ-O)₈(RCOO)₁₆, Where R = CF₃, C₆H₅)─Potential Nanobuilding Units for Tc-MOFs

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach

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Technetium electrochemistry at the turn of the century

Cited by 9 publications

References 111 publications

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Synthesis of Technetium Carboxylates: Wheel-Like Octanuclear Clusters (Tc8(μ-O)8(RCOO)16, Where R = CF3, C6H5)─Potential Nanobuilding Units for Tc-MOFs

Exploring the Reduction Mechanism of99Tc(VII) in NaClO4: A Spectro-Electrochemical Approach

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Synthesis of Technetium Carboxylates: Wheel-Like Octanuclear Clusters (Tc₈(μ-O)₈(RCOO)₁₆, Where R = CF₃, C₆H₅)─Potential Nanobuilding Units for Tc-MOFs

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach