The effect of the electrode composition on electron transfer through an electroactive monolayer

This thesis describes the development of methods for determining the rate constants between a single type of an electroactive self-assembled monolayer on four metals: Au, Pt, Ag, and Hg. Marcus density-of-states theory predicts that the standard rate constant is proportional to the density of states (DOS) of the metal. The DOS increases by a factor of ten for the four metals above. Tafel plots are obtained from which the standard rate constant and the reorganization energy are extracted. Within experimental uncertainty, the standard rate constant is the same on Au, Pt, and Ag. Surprisingly, the reorganization energy is half as large on Ag as it is on Au and Pt. The discrepancy between the model predictions and the results can be attributed to tunneling from only the "s"-band states in the metal. For long-range electron transfer, the composition of the metal does not affect the rate of electron transfer.