Scanning Tunneling Microscopy and Infrared Spectroscopy as Combined In-SituProbes of Electrochemical Adlayer Structure: Cyanide on PT(111)

摘要

The spatial structure of irreversibly adsorbed cyanide adlayers on a Pt(111)electrode is deduced by means of in-situ scanning tunneling microscopy (STM) combined with infrared reflection-absorption spectroscopy (IRAS). The latter data suggests atop-like Pt-CN coordination. The STM images display a (2 sq rt of 3 x 2 sq rt of 3)R30 deg-7CN structure, with cyanides bound in symmetric atop sites surrounded by hexagonal clusters of CN, likely bound in near-atop sites. This arrangement, stable over the applied potential range -0.5 to 0 V vs SCE, gives way to a (2 x 2) structure and disordered adlayers at lower potentials. These findings are compared with previous structural information deduced from ex-situ electron diffraction.