ECSTM study of adsorption of C60, C70, C86 and Y@C82 on Au(111)

The adsorption of a variety of fullerenes (C₆₀, C₇₀, C₈₆, Y@C₈₂) on Au(111) electrode surfaces was comprehensively investigated in 0.1 M HClO₄ by electrochemical scanning tunneling microscopy (ECSTM). In the ordered C₆₀’s adlayer, C₆₀ molecules formed either (2 $ \sqrt 3 $ ×2 $ \sqrt 3 $ ) or “in-phase” structure. The high resolution STM image shows that the C₆₀ cage is not simply round but shows a bifurcated feature. The adsorption orientation of C₆₀ on Au(111) is tentatively suggested. In the ordered C₇₀’s adlayer, the perpendicular fullerene molecules are the main adsorption mode and form (2 $ \sqrt 3 $ ×2 $ \sqrt 3 $ ) structure. However, for C₈₆ and Y@C₈₂, the ordered adlayer could not be obtained on Au(111) under the present condition. These differences may be due to the different molecular shapes and sizes, and the encapsulated metal atom which affects the lattice matches with the substrate. The adsorption of fullerene molecules on Au(111) from disorder to order could be tuned simply by steering the dimensional sizes or shapes of the fullerenes used.