Electrochemical synthesis of metal nanoparticles using a polymeric mediator,whose reduced form is adsorbed (deposited) on an electrode

Efficient mediated electrosynthesis of nanocomposite Au@р(MVCA⁸⁺-co-St) (~6 nm), in which ultrasmall Au nanoparticles (Au-NP) were bound in nanocapsules of water-soluble nanoparticles of соpolymer р(MVCA⁸⁺-co-St) of tetraviologen calix[4]resorcinol (MVCA⁸⁺) with styrene (St), was accomplished by the reduction of Au^I in aqueous medium. The quanti- tative reduction of Au^I was carried out using the theoretically necessary amount of electricity and was not accompanied by the deposition of metal on the electrode. Radical cations of viologen units MV^?+ of the molecule р(MVCA^4?+-co-St) adsorbed on the electrode and π-dimers MV^?+···MV^?+ of π-polymers [р(MVCA^4?+-co-St)] _n deposited on the electrode act- ed as the reducing agents with respect to Au^I. During electrolysis, the nanoparticles agglo- merated to 37—50 nm. The nanocomposite particles dispersed in ethanol had sizes of 72±16 nm and also contained Au-NP with sizes of 51±8 and 19±3 nm. The catalytic activity of the nanocomposite in the reduction of p-nitrophenol with sodium borohydride was demon- strated. A similar reduction of AgCl nanoparticles (~250 nm) led to the formation of silver nanoparticles with crystallite sizes in the range of 7—11 nm, the process was inefficient, however, even when using 250% of electricity, an incomplete reduction of AgCl was still observed.     

Kinetics of the complex-radical polymerization of methyl methacrylate in the presence of initiating metallocene systems

The kinetics of methyl methacrylate polymerization in the presence of benzoyl peroxide + metallocene (ferrocene, titanocene dichloride, and zirconocene dichloride) initiating systems is considered, and the effects of the nature and amount of metallocene in the system are reported. The polymerization is assumed to be a complex-radical process. The structure of the complex-radical sites of chain propagation and a scheme of their formation are deduced from quantum-chemical calculations.     

Two-step one-pot electrosynthesis and catalytic activity of xCoO–yCo(OH)2-supported silver nanoparticles

Journal of Solid State Electrochemistry - Efficient two-step electrosynthesis of xCoO–yCo(OH)2 (CoOxHy)-supported silver nanoparticles (AgNPs) is carried out in N,N-dimethylformamide (DMF)...     

Molecular Oxygen as Mediator in the Metal Nanoparticles’ Electrosynthesis in <Emphasis Type="Italic">N,N</Emphasis>-Dimethylformamide

Ultra-fine gold (<2 nm), silver (5 ± 2 nm), and palladium (<1–2 nm) nanoparticles stabilized in polyvinylpyrrolidone shell were synthesized in N,N-dimethylformamide, using molecular oxygen dissolved in the electrolyte as mediator, by the reduction of the metals’ ions and complexes at the controlled potential of the oxygen reduction to its radical-anion. Pd-nanoparticles showed high catalytic activity in the reactions of p-nitrophenol reduction and Suzuki cross-coupling. Long-term ageing of spherical Ag-nanoparticles for 60 days in the post- electrolysis solution resulted in their consolidation (up to 17 ± 5 nm; the average size of crystallites 7.5 (3) nm). Upon similar exposure of Au-nanoparticles for 15 days, V-shaped nanoparticles were formed (length 112 ± 53 nm, width 58 ± 22 nm, crystallites 20(2)–31(1) nm); upon the isolation, dispersing into ethanol, and exposure for 48 h, hexagonal nanoparticles (105 ± 29 nm) and polygons (56 ± 25 nm, crystallites 24(2)–51(1) nm; upon dispersing into water and exposure for 8 h, spherical nanoparticles (13 ± 8 nm, crystallites 7(1)–13.4(5) nm). Thus obtained nanoparticles are characterized by methods of cyclic voltammetry, dynamic light scattering, scanning and high resolution transmission electron microscopy, and X-ray powder diffraction.     

Effect of strong electrolytes on surface activity of aqueous 1,1-dimethyl-1-alkylhydrazinium chloride in aqueous solutions

The effect of electrolytes on the surface activity of aqueous anionic (1,1-dimethyl-1-alkylhydrazinium chloride homologues with the C₁₀–C₁₈ alkyl radical) and nonionic (Neonol AF 9–12) surfactants in aqueous solutions was studied.     

Electrochemical synthesis of nanocomposite of palladium nanoparticles with polymer viologen-containing nanocapsule

An efficient mediated electrosynthesis of the spherical (85 nm) nanocomposite material Pd@p(MVCA⁸⁺-co-St) was carried out in an aqueous medium. Ultrasmall palladium nanoparticles (3—8 nm) are stabilized in nanocapsules of water-soluble nanoparticles of the copolymer p(MVCA⁸⁺-co-St) consisting of tetraviologen calix[4]resorcinol (MVCA⁸⁺) with styrene (St). The role of the mediator is played by viologen units of a polymer nanoparticle at potentials of the MV²⁺/MV^?+ redox couple. The high catalytic activity of the nanocomposite material in the reduction of nitrophenol with sodium borohydride is shown.     

Growth,crystal structure and transport properties of quasi one-dimensional conductors NbS3

We report synthesis of quasi-one-dimensional conductor NbS₃, TEM studies and transport properties of the prepared samples. The grown NbS₃ whiskers are Peierls conductors known as phase II with the transitions at T_P1=365 K and T_P2=150 K. CDW1 is stable and not so sensitive to growth conditions. It can slide and be synchronized by the external microwave irradiation up to 16 GHz. CDW2 strongly depends on growth conditions. Nevertheless, it also shows sliding and synchronization.     

Two-step electrosynthesis and catalytic activity of CoO−CoO • xH2O-supported Ag,Au, and Pd nanoparticles

Russian Chemical Bulletin - Two-step electrosynthesis of CoO-CoO?xH2O-supported metal nanoparticles (MNPs, M = Au, Ag, Pd) was carried out in N,N-dimethylformamide in the absence and in...     

Electrosynthesis of nanocomposites of Ag,Au, Pd nanoparticles with aluminum(III), zinc(II), and titanium(IV) oxide-hydroxides

Journal of Solid State Electrochemistry - The two-step electrosyntheses of metal nanoparticles (MNP) (M = Pd, Ag, Au) nanocomposites with aluminum(III), zinc(II), titanium(IV)...