Electrochimica Acta, Vol.198, 185-194, 2016
Chemisorption Threshold of Thiol-based Monolayer on Copper: Effect of Electric Potential and Elevated Temperature
Coating of self-assembled monolayer (SAM) on metal surfaces for corrosion protection and adhesion promotion is gaining increasing interest. One of the major obstacles for this technology is the time required for SAM deposition. Preparing SAMs electrochemically has recently come to prominence due to the time reduction of the SAM deposition process. Additionally, the externally applied electric potentials are critically important in enhancing the quality and the surface coverage of SAM on metal substrates. In this work, thiol-based SAM adsorption was investigated under various applied electric potential values and its impact on the adsorption rate constant was studied. The results demonstrated that there exists a SAM adsorption potential threshold in which the adsorption rate constant k(t) could be one order higher than its normal values. At an applied potential near potential of zero charge (phi(pzc)), the charge on the Cu electrode surface is close to neutral, making adsorption of SAM energetically favorable. A SAM mass transport model under the influence of an external energy field was proposed in which both calculated and experimental results were compared and discussed. These findings are shown to provide key mechanistic insight and help rationalize the selection of the externally applied electric potential in order to enhance the SAM adsorption process. (C) 2016 Elsevier Ltd. All rights reserved.