Coverage dependent behavior of redox reaction induced structure change and mass transport at an 11-ferrocenyl-1-undecanethiol self-assembled monolayer on a gold electrode studied by an in situ IRRAS–EQCM combined system

Abstract

The potential dependent structure change and mass transport at an 11-ferrocenyl-1-undecanethiol (FcC 11 SH) self-assembled monolayer on a gold electrode with various coverages were investigated by simultaneous Fourier transform infrared reÑection absorption spectroscopy (IRRAS) and electrochemical quartz crystal microbalance (EQCM) measurements in 0.1 M solution. As soon as the terminal ferrocene group was HClO 4 oxidized to a ferricenium cation (Fc`), a number of upward and downward IRRAS bands were observed and the surface mass was increased. The intensity of the IRRAS bands corresponded well with the mass change. This behavior is attributed to the redox reaction induced orientation change in the monolayer and FcC 11 SH ion pair formation between the Fc`cation and the perchlorate anion in solution. The monolayer FcC 11 SH with a lower coverage was less stable and was decomposed at a less positive potential than that with a high coverage. Models are proposed to explain the coverage dependent behavior of the monolayer FcC 11 SH induced by the redox reaction of the terminal ferrocene moiety.

Heterogeneous electron transfer kinetics and electrocatalytic behaviour of mixed self-assembled ferrocenes and SWCNT layers

“…For example, Collman et al 6 used ferrocene adsorption to demonstrate the applicability of Sharpless ''click'' chemistry as a general methodology for functionalizing surfaces coated with self-assembled monolayers. Chidsey and co-workers 2 studied co-adsorbed ferrocene and unsubstituted alkanethiol and observed the structural orientation/changes that accompany concentration changes; Aluletta et al 7 studied mixed SAMs of ferrocene-terminated thiols and hydroxyalkanethiols and proved the occurrence of phase separations; Ye et al 8 observed coverage-dependent behavior of the ferroceneterminated thiol SAMs induced by the redox reaction of the terminal ferrocene moiety, while Waldeck and co-workers showed how intermolecular electronic coupling pathways could contribute to the electron transfer; Uosaki and co-workers 10 studied SAM containing both ferrocene and azobenzene moieties and established how electro-and photochemical structural conversion of the cis and trans forms of the azobenzene moiety could impact on the charge-transfer processes; Crooks and co-workers 11 studied mixed monolayers of ferrocene-dendrimers and alkanethiols and, for the first time, introduced an elegant strategy for constructing an electrochemical current rectifier that permits current flow in only one direction; and Chambers et al 12 reported how a ferrocene-thiol SAM co-adsorbed with alkanethiolates could unravel nanoscale phase separation.…”

Construction of multilayers of bare and Pd modified gold nanoclusters and their electrocatalytic properties for oxygen reduction

“…The wave due to the redox of the ferrocene moiety decreased as the potential cycle was repeated and disappeared after about 20 cycles. These results show that the anodic current was due to both the formation of Au oxide and anodic oxidation of the SAMs at the GNC surface, which proceeds as follows [34]:…”

Size dependent lattice constant change of thiol self-assembled monolayer modified Au nanoclusters studied by grazing incidence x-ray diffraction

“…When the potential was made more positive than that for the oxidative decomposition of the thiol SAM on gold [32][33][34][35], the SAM was gradually removed from the GNCs and GNCs started to aggregate [22,23].…”