A new simple method to heal defects and to improve electrode passivity of aromatic SAMs on gold

• Aromatic SAMs increase electrode passivation properties upon exposure to H2O.
• The new preparation protocol leads to more stable and less defective aromatic SAMs.
• The method is more effective for benzenethiol than for naphtalenethiol SAMs.

In the present work we report a new, simple method to heal the defects of SAMs constituted by small aromatic thiols, namely benzenethiol (BT) and 2-naphthalenethiol (2-NT), on polycrystalline Au surfaces. The method consists in the alternate immersion of the Au substrate in the thiolic solution and in ultrapure water. The layers obtained with the new protocol were characterized by means of Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS), and were compared with SAMs prepared with the traditional adsorption procedure. The results show that our treatment leads to a remarkable increase of the blocking behavior of the layers, indicating a decrease in density of defective sites, and to an improvement of the SAM stability. On the basis of the obtained results, a possible explanation to this phenomenon is proposed.

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