title: Stabilizer-free silver nanoparticles as efficient catalysts for electrochemical reduction of oxygen.
abstract: In this work we demonstrated the potential of the He+5% H2+1% N2plasma jet treatment for the synthesis of surfactant-free silver nanoparticles (Ag NPs) with narrow size distribution. The obtained colloidal solutions of electrostatically stabilized Ag NPs do not show any agglomeration for several months. Apart from an atomic thin oxide layer and the relatively weakly bound OH-ions, the surface of Ag NPs can be considered as stabilizer-free. The surface charge (characterized by the zeta potential) of Ag NPs in solution was measured by electrophoretic light scattering technique. Plasmonic band position and width in the UV/VIS extinction spectra was utilized for the assessment of Ag NPs size distribution. Highly concentrated Ag NPs were uniformly deposited on the surface of the glassy carbon (GC) electrodes by vacuum-drying technique. The deposition process was monitored with a digital camera attached to a microscope. The assemblies of Ag NPs on the electrode surface were characterized by scanning electron microscopy. The Ag NP/GC catalysts were electrochemically tested in alkaline solution using the rotating disk electrode method. The Ag NP/GC electrodes exhibited high electrocatalytic activity toward the oxygen reduction reaction (ORR) in 0.1M KOH solution, indicating their potential applicability as cathode materials for alkaline fuel cells.
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia. Electronic address: atr@ut.ee.
authors.forename: Alexey
authors.initials: A
authors.lastname: Treshchalov
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.
authors.forename: Heiki
authors.initials: H
authors.lastname: Erikson
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia.
authors.forename: Laurits
authors.initials: L
authors.lastname: Puust
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Tsarenko
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia.
authors.forename: Rando
authors.initials: R
authors.lastname: Saar
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Vanetsev
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia. Electronic address: kaido.tammeveski@ut.ee.
authors.forename: Kaido
authors.initials: K
authors.lastname: Tammeveski
authors.affiliation: Institute of Physics, University of Tartu, W. Ostwald 1, 50411 Tartu, Estonia.
authors.forename: Ilmo
authors.initials: I
authors.lastname: Sildos
keywords: Bipolar pulse discharge; Electrocatalysis; Electrostatic stabilization; Oxygen reduction; Silver nanoparticles; Vacuum drying