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.
In addition to explaining the phenomenon of Electrochemical Promotion in Heterogeneous Catalysis when using Na-β″-Al2O3 solid electrolyte these observations provide the first STM confirmation that:
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.
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Makri, M., Vayenas, C.G., Bebelis, S. et al. Atomic resolution scanning tunneling microscopy imaging of Pt electrodes interfaced with β″-Al2O3 . Ionics 2, 248–253 (1996). https://doi.org/10.1007/BF02376030
- Catalytic Activity
- Scan Tunneling Microscopy
- Solid Electrolyte
- Heterogeneous Catalysis