Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (01): 163-168.doi: 10.3866/PKU.WHXB20101219

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Effect of Alkyl Chain Length on the Structure of Viologen Adsorbed on a Cu(100) Electrode

JIANG Min1, ZHANG Hong-Yu2, ZHAO Xue-Bo1   

  1. 1. Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong Province, P. R. China;
    2. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, Shandong Province, P. R. China
  • Received:2010-07-14 Revised:2010-09-01 Published:2010-12-31
  • Contact: JIANG Min
  • Supported by:

    The project was supported by the Alexander von Humboldt Foundation of Germany.


The redox behavior and the potential dependent adsorption structure of alkylated viologen on a Cu(100) electrode were investigated by cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM). Heptyl viologen (1,1'-diheptyl-4,4'-bipyridinium dichloride) (DHV) and ethyl viologen (1,1'-diethyl-4, 4'-bipyridinium dibromide) (DEV) showed different current waves during CV measurements in a KCl-containing electrolyte solution. The dicationic heptyl viologen molecules showed a highly ordered two dimension (2D)‘dot-array’structure on the c(2 × 2)-Cl modified Cu(100) electrode surface in the STM images while the dicationic ethyl viologen molecules did not show any structures. With a decrease in the electrode potential, a one-electron reduction of the dication heptyl viologen resulted in the appearance of a stripe pattern that was formed by radical heptyl viologen as shown in the STM images. A more compact stripe pattern was visible in the radical ethyl viologen phase. The adsorption structure of heptyl viologen strongly depends on the electrode potential but the structure of the ethyl viologen adsorbed on the Cu(100) electrode was less response to the electrode potential.

Key words: Electrochemical scanning tunneling microscopy, Cyclic voltammetry, Viologen, Length of alkyl chain, Potential-dependent