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 calix4]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.