Kinetics behavior of long-chain n-alkanethiols adsorbed on copper surface

Abstract

The adsorption of n-alkanethiols (CH3(CH2)n−1SH) self-assembled monolayers on copper surface was investigated by electrochemical impedance spectroscopy. The variation of surface coverage versus time was obtained by charge transfer resistances and interfacial capacitance in the impedance. It was found that the adsorption process was consistent with Langmuir kinetics model, no matter changes in chain length and concentration of thiols. Based on the established model, the different adsorption and desorption rate constants were calculated to describe the adsorption process on copper surface. Furthermore, the variation of ka was revised when the concentration of thiols in solution was changed. According to our model and revised ka, the effects are explained on the basis of the diffusion and interaction between thiols and solvent in the formation of thiols SAMS on copper surface.