Mendeleev Commun., 2017, 27, 274–277 – 274 – Mendeleev Communications © 2017 Mendeleev Communications. Published by ELSEVIER B.V. on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences. The interest in metal nanoparticles (M-NPs) has been increasing lately due to their unique properties and diverse potential appli- cations in catalysis, electronics, biomedicine, optics, analysis, etc. 1–7 Currently, chemical reduction of metal ions and metal complexes in solution is the most thoroughly developed and popular method for their synthesis. For example, Au-NPs were prepared using a number of different reducing agents, in particular, hydrogen, 8 sodium citrate, and ascorbic acid. 9 Electroreduction of metal ions and metal complexes is widely used for M-NP preparation on an electrode surface 10 and is rather rarely used for the electrosynthesis of M-NPs in bulk solution. Deposition of metals generated on the electrode surface is the main factor that restricts the use of electrochemistry. Therefore, in all developed methods for M-NP electrosynthesis in bulk solution the deposi- tion problem has to be solved. In the pulse sonoelectrochemistry method, 11–13 the formation of NPs on the electrode surface during short-time electroreduction is combined with their subsequent transfer to the solution by sonication of the electrode. In the method developed by Reetz et al., 14–18 the electroreduction of ions is performed in aprotic organic media using tetraalkyl- ammonium or phosphonium salts as supporting electrolytes. For the same purpose, we have suggested the mediated electro- synthesis method, 19–28 which differs from those mentioned above by moving the step of metal ion reduction from the electrode surface to the bulk solution. In this case, a mediator is reduced on the cathode, then reduced form of the mediator diffuses into the solution and reduces metal ion or metal complex. Thus, metal deposition on the electrode is minimized or completely avoided. The method applicability and efficiency were recently demon- strated by preparing Pd, 19–21 Ag, 22,23 Co, 24 Au, 25–27 and Pt NPs. 28 The following compounds were used as the mediators: methyl- viologen (MV 2+ ), either free or immobilized on the calix[4]- resorcin platform, anthracene, oxygen, and C 60 fullerene. Au-NPs were obtained by electroreduction of Au I in two-compartment cell using MV 2+ , oxygen, and fullerene as the mediators. In this paper, we report the electrosynthesis of Au-NPs stabilized with poly(N-vinylpyrrolidone) (PVP). The electro- synthesis was performed by in situ generation of metal ions from the Au anode in aqueous media and by reduction with methyl- viologen in single compartment cell. It is known 29 that active anodic dissolution of gold in aqueous media occurs in the presence of chloride ions. Therefore, 0.1 M NaCl was used as supporting electrolyte. The cyclic voltammetry (CV) curves of the gold electrode in this electrolyte exhibit active dissolution at 0.80–1.30 V vs. SCE and an electrode passivation at more positive potentials (Figure 1). The reverse CV curve demonstrates two re-reduction peaks C 1 and C 2 at 0.70 and 0.48 V, respectively. The C 1 peak is con- siderably weakly expressed, and C 2 is the main peak corre- sponding to the re-reduction of the generated gold ions. If the scanned potentials are limited to the active dissolution region, the shape of the reverse CV branch remains the same, but the C 2 peak is slightly (by 40 mV) shifted to less anodic potentials. Reduction of Au I (AuCl or [AuCl 2 ] – ) 25 and HAuCl 4 occurs at similar potentials; the peak potentials on a glassy carbon (GC) electrode are 0.22 and 0.30 V, respectively (Figures S1 and S2, Online Supplementary Materials). Therefore, CV curves show that gold anode is dissolved, but do not provide information about the oxidation product. The nature of the C 1 peak also remains unclear. Electrosynthesis of gold nanoparticles mediated by methylviologen using a gold anode in single compartment cell Vitaliy V. Yanilkin,* a Natalya V. Nastapova, a Gulnaz R. Nasretdinova a and Yurii N. Osin b a A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Centre, Russian Academy of Sciences, 420088 Kazan, Russian Federation. Fax: +7 843 275 2253; e-mail: yanilkin@iopc.ru b Interdisciplinary Center for Analytical Microscopy, Kazan (Volga Region) Federal University, 420018 Kazan, Russian Federation DOI: 10.1016/j.mencom.2017.05.019 MV + Au + Au MV 2+ Au 0 + e – – e – – + PVP (Au 0 ) n Methylviologen mediated reduction of Au I 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. 10 5 0 –5 j /mA cm –2 0.0 0.5 1.0 1.5 E/V vs. SCE 1 2 C 1 C 2 Figure 1 CV curves recorded on an Au electrode in aqueous 0.1 M NaCl solution in the potential region of (1) 1.5–0.0 V and (2) 1.1 to –0.3 V. u = 100 mV s –1 .