Electrochemical behavior of silver thin films interfaced with yttria-stabilized zirconia
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Thin silver films (100–800 nm) were deposited by physical vapor deposition (PVD) on yttria-stabilized zirconia solid electrolyte. The electric percolation as a function of the film thickness was studied during deposition and annealing using a two-electrode in-situ resistance measurement technique. Electrical percolation was achieved in as-deposited films greater than 5.4 ± 0.4 nm; however, thermal treatment (550 °C in air) resulted in film dewetting for Ag films as thick as 500 nm and formation of electronically isolated Ag nanoparticles, as was confirmed by SEM and XPS. In thermally treated samples, stable electronic conductivity associated with a continuous percolated network was only observed in samples greater than 600 nm in thickness. The effect of polarization on the electrochemical reactions at the three-phase (electrode-gas-electrolyte) and two-phase (electrode-electrolyte) boundaries of the electrode was investigated by solid electrolyte cyclic voltammetry (SECV) at 350 °C and P O2 = 6 kPa. With the application of positive potential, silver oxide (Ag2O) was found to form along the three-phase boundary and then extends within the bulk of the electrode with increasing anodic potentials. By changing the hold time at positive potential, passivating oxide layers are formed which results in a shift in favor of the oxygen evolution reaction at the working electrode. This oxide forms according to a logarithmic rate expression with thick oxides being associated with decrease in current efficiency for subsequent oxide formation.
KeywordsSilver Thin film PVD Yttria-stabilized zirconia Cyclic voltammetry Percolation
Financial support from the Natural Science and Engineering Research Council (NSERC), Canada is gratefully acknowledged.
- 19.Baiker A, Kilo M, Maciejewskiq M et al (1993) Hydrogenation of CO2 over copper, silver and gold-zirconia catalyst: comparative study of catalyst properties and reaction pathways. New Frontiers in Catalysis. pp 5071–5080Google Scholar
- 24.Vayenas CG, Bebelis S, Brosda S et al (2002) Electrochemical promotion of catalysis promotion, electrochemcial promotion and metal support interactions. Kluwer Academic Publishers, New YorkGoogle Scholar
- 25.Wagner C (1970) Adsorbed atomic species as intermediates in heterogeneous catalysis. In: 21 (ed) Adv. Catal. Academic Press Inc., London, pp 323–378Google Scholar
- 28.Falgairette C (2010) Stored electrogenerated promoters inducing sustainable enhanced Pt catalyst activity. Sciences-New York 4690:230Google Scholar
- 33.Briggs D, Seah MP (1996) Practipuis, vol. 1, 2nd edn. Wiley, New YorkGoogle Scholar
- 40.Bukhtiyarov V, Kondratenko V, Boronin AI (1993) Features of the interaction of a CO + O2 mixture with silver under high pressure. Surf Sci Lett 293:L826–L829Google Scholar
- 44.Palloukis F, Zafeiratos S, Jaksic M, Neophytides SG (2004) The chemical state of electrodeposited thin Cr films on a polycrystaline Ni foil. J New Mater Electrochem Syst 7:173–177Google Scholar
- 52.Bard AJ, Faulkner LR (2001) Electrochemical methods - fundamentals and applications, 2nd Ed. 864Google Scholar
- 53.Abd El Rehim SS, Hassan HH, Ibrahim MAM, Amin MA (1998) Electrochemical behaviour of a silver electrode in NaOH solutions. Monatsh Chem 129:1103–1117Google Scholar