A study of 1-decanethiol self-assembly on gold electrodes by computer simulation

This work is a preliminary study towards the understanding of the adsorption and self-assembly mechanisms of alkylthiols on gold electrodes. Canonical Monte Carlo simulations were performed at 298 K. The simulated model consisted of diluted solutions of 1-decanethiol in ethanol inside two gold electrodes, at the potential of zero charge. Three potentials for the oxygen-gold surface interaction were used. The liquid phase molecules were taken as rigid. The average tilt angle of the thiol molecule adsorbed on a Au(1 1 1) flat surface and the density profiles were determined. The approach of the thiol to the electrode was analyzed by calculating the variation of the Helmholtz energy along the normal to the surface. The average tilt angle is in good agreement with experimental data. Finally, we suggest possible improvements to the present model.