Study of the Formation Process of an Azobenzene Self-assembled Monolayer on Gold Surface

The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol, denoted as AzoC2SH on gold surface was studied using electrochemical techniques, and the monolayers prepared at different assembly times and concentration were also investigated. A two-step adsorption kinetics has been confirmed: the fast adsorption process and the following long-term reorganization. The equilibrium constant (K) for the adsorptioon and the interaction factor between adsorbate-adsorbate molecules (δ) were evaluated based on the Frumkin isotherm and determined to be (3.17±0.13)×10⁶ mol·L^-1 and -0.34±0.04, respectively. The Gibbs free energy (ΔG) of SAM was determined to be -(37.07±0.13) kJ·mol^-1.