Atomic resolution scanning tunneling microscopy imaging of Pt electrodes interfaced with β″-Al2O3
Solid electrolytes can be used as active catalyst supports to induce significant and reversible catalytic activity and selectivity enhancement via the effect of Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA effect) or Electrochemical Promotion which has been recently reported for over fourty catalytic reactions.
Atomically resolved Scanning Tunneling Microscopy was used to image the reversible electrochemically controlled dosing (backspillover) of sodium on Pt(111) interfaced to β″-Al2O3 at atmospheric pressure, which has been proposed as the cause of the NEMCA effect in the case of Na+ conductors.
It was found that electrical current application between the Pt(111) monocrystal and a counter electrode also in contact with the β″-Al2O3 Na+-conducting solid electrolyte causes reversible migration (backspillover and spillover) of sodium which forms a (12×12) hexagonal structure on the Pt(111) surface.
spillover-backspillover phenomena can take place over enormous (~mm) atomic distances, and
promoters can form ordered structures on catalyst surfaces under ambient conditions relevant to industrial practice.
KeywordsAl2O3 Catalytic Activity Scan Tunneling Microscopy Solid Electrolyte Heterogeneous Catalysis
Unable to display preview. Download preview PDF.
7. References and Notes
- C.G. Vayenas, M.M. Jaksic, S. Bebelis and S. Neophytides “The Electrochemical Activation of Catalytic Reactions” in “Modern Aspects of Electrochemistry”, J.O'.M. Bockris, B.E. Conway and R.E. White, Eds., Vol.29, pp. 57–202, Plenum Press, New York (1995) and references therein.Google Scholar
- M. Makri, A. Buekenhoudt, J. Luyten and C.G. Vayenas, Ionics2, 000 (1996).Google Scholar
- B. Grzybowska-Swierkosz and J. Haber in “Annual Reports on the Progress of Chemistry”, Vol. 91, pp. 395–439, The Royal Society of Chemistry, Cambridge (1994).Google Scholar
- W. Zipprich, H.-D. Wiemhöfer, U. Vöhrer and W. Göpel, Ber. Bunsengesel. Phys. Chem.99, 1406 (1995).Google Scholar
- D.I. Kondarides, G.N. Papatheodorou, C.G. Vayenas and X.E. Verykios, Ber. Bunsengesel. Phys. Chem.97, 709 (1993).Google Scholar
- C.J. Chen “Introduction to Scanning Tunneling Microscopy” Oxford University Press (1993) and references therein.Google Scholar
- A.J. Arvia and R.C. Salvarezza, Electrochim. Acta11/12, 1481 (1994).Google Scholar
- R. Sonnenfeld, J. Schneir and P.K. Hansma in Modern Aspects of Electrochemistry, R.E. White and J.O'. M. Bockris, Eds. Vol. 21, pp. 1–28, Plenum Press, New York (1990).Google Scholar
- B. Delmon in “New Aspects of Spillover Effect in Catalysis” T. Inui, K. Fujimoto, T. Uchijima, M. Masai Eds., pp. 1–9 Elsevier, Amsterdam (1993); S.J. Teichner, ibid pp. 27–45.Google Scholar
- K.J. Uram, L. Ng and J.T. Yates, Jr. Surf. Sci.177, 253 (1986).Google Scholar
- M. Makri, C.G. Vayenas, S. Bebelis, K.H. Besocke and C. Cavalca, Surf. Sci.000, 000 (1996).Google Scholar