Atomic resolution STM imaging of electrochemically controlled reversible promoter dosing of catalysts

[摘要] Reversible electrochemically controlled dosing (back-spillover) of sodium on Pt(111) at atmospheric pressure was imaged via atomically resolved STM. The Pt(111) monocrystal was interfaced with a flat polycrystalline sample of beta ''-Al2O3, it Na+ conductor. Application of an electrical current between the Pt(111) monocrystal and a counterelectrode also in contact with the beta ''-Al2O3 Na+-conducting solid electrolyte causes reversible migration (back-spillover and spillover) of sodium, which forms a (12 x 12) hexagonal structure on the Pt(111) surface. In addition to explaining the phenomenon of electrochemical promotion in heterogeneous catalysis, these observations provide the first STM confirmation of spillover phenomena which play a key role in numerous catalytic systems.

[发布日期] 1996-12-20

[关键词] catalysis;electrochemical methods;metal-solid electrolyte interfaces;platinum;promotion;scanning tunneling microscopy;sodium;surface diffusion