In Situ Scanning Tunneling Microscope of Cyanide and Thiocyanate Adsorption on Pt(111)

  • Yau, Shueh-Lin (Itaya Electrochemiscopy Project, ERATO/JRDC, Research Institute of Electric and Magnetic Materials) ;
  • Kim, Youn-Geun (Itaya Electrochemiscopy Project, ERATO/JRDC, Research Institute of Electric and Magnetic Materials) ;
  • Itaya, Kingo (Faculty of Engineering, Tohuku University)
  • Published : 1995.12.25

Abstract

Cyclic voltammetry and in situ STM were employed to examine the interfacial structures of a Pt(111) electrode in 0.1 mM KCN (pH9.5) and 0.1 mM KSCN (pH7) solutions. In situ STM atomic resolution revealed well ordered (2${\surd}$3${\times}$2${\surd}$3)$R30^{\circ}$-6CN and ($2{\times}2$)-2SCN structures within the double layer charging region. Six CN adsorbates formed a hollow hexagon, which embraced a coadsorbed $K^+$ cation. In contrast, the coadsorbed $K^+$ cations on the SCN covered Pt(111) were poorly ordered, despite adsorbed SCN formed a long range ordered ($2{\times}2$)-2SCN adlattice. In situ STM revealed the pronounced influence of potential in controlling the structures of compact layers at the proximity of a Pt electrode. Cathodic polarization facilitated the replacement of the coadsorbed cations by protons.

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