Anthracene mediated electrochemical synthesis of metallic cobalt nanoparticles in solution

© 2015 Elsevier Ltd. All rights reserved. The metallic cobalt nanoparticles in the bulk solution were obtained by antracene mediated reduction of [CoCl4]2- in the potentiostatic electrolysis in an undivided cell at the potential of the anthracene reduction to radical anion at room temperature in DMF/0.1 M Bu4NCl media. [CoCl4]2- ions are generated by the sacrificial cobalt anode dissolution during the electrolysis. The metal particles are oxidized upon contact with the air to form the oxidized cobalt nanoparticles with a low dispersity (20-30 nm)

Radiation-induced damage and evolution of defects in Mo

The formation of defects in bcc Mo lattice as a result of 50-keV Xe bombardment is studied via atomistic simulation with an interatomic potential developed using the force-matching ab initio based approach. The defect evolution in the cascade is described. Diffusion and interaction of interstitials and vacancies are analyzed. Only small interstitial atom clusters form directly in the cascade. Larger clusters grow only via aggregation at temperatures up to 2000 K. Stable forms of clusters demonstrate one-dimensional diffusion with a very high diffusion coefficient and escape quickly to the open surface. Point vacancies have much lower diffusivity and do not aggregate. The possibility of a large prismatic vacancy loop formation near the impact surface as a result of fast recrystallization is revealed. The mobility of the vacancy dislocation loop segments is high, however, the motion of the entire loops is strongly hindered by neighbor point defects. This paper explains the existence of the large prismatic vacancy loops and the absence of the interstitial loops in the recent experiments with ion irradiation of Mo foils

Electron transfer and subsequent reactions during electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid

The electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid (3,4-dichloro-5-hydroxyfuran-2(5H)-one) in MeCN-Bu 4NBF4 (0.1 mol L-1) was investigated. It was shown that all sulfides are electrochemically active, from one to five oxidation steps of sulfur-containing groups were observed for them. The ease and direction of oxidation of the thio group depend on its nature and position in the furanone ring. 3-Substituted 2(5H)-furanones possess the lowest oxidation potential. 4-Substituted 2(5H)-furanones are predominantly oxidized to sulfoxides, 5-aryl- and -alkylthio derivatives undergo fragmentation to give mucochloric acid, and 3-arylthio derivative gives complex unidentified mixture of products. In the case of 3,4-bis(4-methylphenylthio) derivative, the oxidation product of the arylthio group at the 3 position to the corresponding sulfoxide was isolated. Based on the data from cyclic voltammetry with different concentrations of a substrate and water added, the results of preparative electrolysis and quantum chemical calculations, possible mechanisms of electrochemical oxidation of mucochloric acid-derived sulfides are discussed. The initial common step is a reversible single-electron transfer from the substrate molecule to form highly reactive radical cation. © 2009 Springer Science+Business Media, Inc

Methylviologen mediated electrosynthesis of palladium nanoparticles stabilized with CTAC

© 2016 The Electrochemical Society. All rights reserved.Efficient electrosynthesis of ultrasmall palladium nanoparticles stabilized with CTA+ cetyltrimethylammonium cations (Pd@CTA+) was carried out in an aqueous medium by methylviologen mediated electroreduction of poorly soluble aggregates ([PdCl4]2·2CTA+)n of [PdCl4]2- anionic complex with CTA+ cations on a glassy carbon electrode at potentials of theMV2+/MV·+ redox couple. ([PdCl4]2- ·2CTA+)n aggregates are reduced directly on the electrode at a low rate and the generated metal is deposited on the electrode. In the case of mediated reduction, the metal is not deposited on the cathode, and after passing of Q = 2 F quantitative conversion from [PdCl4]2- to Pd@CTA+ nanoparticles occurs in the solution bulk. These particles are positively charged (zeta-potential is 66.8 mV) and their hydrodynamic diameter is 18 nm. Separated Pd@CTAC nanoparticles are combined into larger aggregates due to coalescence of the organic shell. The predominant shape of metal nanoparticles is an imperfect sphere with a diameter of 5 ± 3 nm, and the average size of the metal crystallites is 4.66 nm

Electrosynthesis of gold nanoparticles mediated by methylviologen using a gold anode in single compartment cell

© 2017Methylviologen mediated reduction of AuI ions generated in situ by dissolution of a gold anode in single compartment cell has been used for the electrosynthesis of spherical gold nanoparticles (Au-NPs) stabilized by poly(N-vinylpyrrolidone). The size of Au-NPs was from 15±6 to 27±9 nm, depending on the electrosynthesis conditions. Au-NPs were characterized by cyclic voltammetry, UV-VIS spectroscopy, dynamic light scattering, scanning and transmission electron microscopy

Electrochemically driven molecular rotors based on ferrocene-1,1'-diyl-bisphosphinic acids

© 2015, Pleiades Publishing, Ltd. Based on ferrocene-1,1'-diyl-bisphosphinic acids Fc[P(R)(O)OH]2 (R = H, Me, Et, Ph) in methanol, two types of electrochemically driven molecular rotors are developed. Monoanions of acids are fixed in the cis-conformation due to the presence of an intramolecular hydrogen bond, whereas dianions are fixed in the trans-conformation due to electrostatic repulsion forces. Upon the transformation of monoanions to dianions, the controlled rotation of cyclopentadienyl rings from cis to trans-conformation occurs; the reverse switching leads to the reverse rotation. In one type of rotors, the rotation is controlled by the reversible variation of the solution pH and composition in the electrochemical oxidation-re-reduction cycle of N-phe-nyl-N'-isopropyl-1,4-phenylenediamine; in the other type, the rotation is determined by the one electron oxidation-re-reduction of the ferrocene nucleus in monoanions. The latter rotor type at room temperature can operate stably only for a short time (τ< 1 s) and at longer times is irreversibly destructed during the oxidation stage

Methylviologen mediated electrochemical synthesis of catalytically active ultrasmall bimetallic PdAg nanoparticles stabilized by CTAC

© 2018 Elsevier Ltd Efficient electrosynthesis of the monodisperse ultrasmall spherical mono- and bimetallic nanoparticles (NP) of Ag and Pd stabilized in the CTAC shell in solution bulk was carried out by methylviologen mediated reduction of equimolar amounts of Pd(II) and Ag(I) (1.5 mM) in the presence of CTAC (75 mM) at controlled potentials of the MV2+/MV•+ redox couple in water/0.1 M NaCl medium at room temperature. Metal ions are quantitatively converted to NP upon consumption of the theoretical amount of electricity. Sizes of isolated PdNP and AgNP are 5 ± 1 nm and 18 ± 5 nm, respectively. Bimetallic PdAgNP were obtained in three ways: (i) by preliminary synthesis of PdNP and subsequent reduction of AgCl (Pd/AgNP); (ii) by preliminary synthesis of AgNP and subsequent reduction of PdCl2 (Ag/PdNP); (iii) by joint reduction of PdCl2 and AgCl (Ag-PdNP). In all cases, a solid-solution alloy PdAgNP is obtained. The driving force for the alloy formation is the energy gain of ∼33 kJ/mol of an alloy. In the first way, the NP size (8 ± 2 nm) and the Pd content in the alloy (76%) are slightly higher than in the other two methods (6 ± 1 nm, 50 and 68%), but the alloy crystallite size (2–5 nm) in NP is the same. PdNP and alloys NP exhibit a high catalytic activity toward the p-nitrophenol reduction and the Suzuki-Miyaura cross-coupling reactions. In the reduction reaction, an addition of silver to palladium decreases the catalytic activity of NP. The catalytic activity of alloys in the coupling reaction correlates with the Pd content in an alloy. And the catalytic activity of the alloy Pd/AgNP obtained in the first method of the NP preparation is higher than that of PdNP

Molecular oxygen as a mediator in the electrosynthesis of gold nanoparticles in DMF

© 2016 Elsevier B.V.The possibility of using of molecular oxygen as a mediator in electrosynthesis of metal nanoparticles by reduction of their ions and complexes in aprotic media was demonstrated by the example of electrosynthesis of gold nanoparticles by reduction of Au(I) in DMF