Effect of pH on the barrier properties of 11-mercapto undecanoic acid and 4-amino thiophenol SAMs on gold

摘要

To understand the influence of surface charge on the electron transfer properties of ionic SAMs, the effect of pH of electrolytic solutions and applied potential on the barrier properties of 11-mercapto undecanoic acid and 4-amino thiophenol SAMs on gold were carried out. We find that 11-mercapto undecanoic acid SAM exhibits poor blocking behaviour towards ruthenium (III) redox reaction at low pH, but shows excellent blocking behaviour at high pH. On the other hand, the same monolayer shows excellent blocking behaviour to ferrocyanide redox reaction even at low pH. On the other hand, 4-aminothiophenol SAM shows poor blocking behaviour towards ferrocyanide and ruthenium (III) redox reaction at low pH, but shows good blocking behaviour at high pH.