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Efficient two-step methylviologen (MV2+) — mediated electrosynthesis of a nanocomposite of gold nanoparticles with copper(I) oxide stabilized by a shell of poly(N-vinylpyrrolidone) (Au/Cu2O@PVP) was performed in DMF at room temperature at the potentials of MV.+ radical cation generation. At the first step, the mediated reduction of Cu2+ ions, generated in situ by dissolution of the copper anode, in the presence of dissolved oxygen or with subsequent oxidation with oxygen, leads to Cu2O@PVP composite containing Cu(0) and Cu2O in a different ratio. In the latter case, the resulting composite is in the form of stable nanoroses. When AuCl is added into the resulting solutions of Cu2O@PVP, the partial chemical reduction of AuCl by Cu(0) occurs to form Au(0) and CuCl. At the second step, the electrochemical reduction of AuCl leads to Au/Cu2O@PVP nanocomposite not containing Cu(0), but nanoroses are preserved. Cu2O@PVP nanoparticles are catalytically inactive in the reduction reaction of p-nitrophenol with sodium borohydride in water, and Au/Cu2O@PVP nanocomposites exhibit catalytic activity. In the presence of cetyltrimethylammonium chloride, the catalytic activity of both types of particles sharply increases; in the case of Cu2O@PVP, the increase is so high that the catalytic activity becomes the same as for Au/Cu2O@PVP.

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A thin‐film styrene polymer–carbon nanoparticle composite was obtained in a single‐stage alternating current dielectric barrier discharge plasma‐chemical process. The allotropic forms of the carbon nanoparticle filler were traced by transmission electron microscopy (TEM). TEM revealed an extraordinary adhesive encapsulation of the carbon nanoparticles by the polymer. It was found that the corona discharge regime provides an onion‐like carbon filler that enhances the mechanical strength and chemical resistance of the synthesized polymer–carbon nanoparticle film. Measurements of the electrical properties of the films implicitly confirmed the uniformity of the carbon filler distribution.