Thin Aqueous Layer on Electrodes

Following the layer-by-layer deposition method pioneered by Decher et al. [282], Cheng and Corn have demonstrated [283] that it was possible to form an aqueous thin layer on a solid electrode by modifying the electrode surface with charged groups, such as by adsorption of mercapto-undecanoic acid on gold, and then 

A major interesting characteristic of these films is their ability to be loaded with charged nanoparticles as shown by Santos et al. [287], which can, in certain cases, mediate electron transfer through the film, as shown by Fermin et al. [288]. Quantum dots have also been incorporated in aqueous thin films to form photoanodes or photocathodes [289,290]. 

An alternative method is to deposit an aqueous drop on a solid electrode such as a silver-silver chloride electrode or a platinum electrode and immerse it in an organic solvent [291]. This method provides a fast and convenient method to measure standard transfer potentials, for example, of ionized drug molecules. It differs from the three-phase junction discussed in the following text, in the sense that the electrode is in contact with one phase only, namely, the aqueous one. In this case, we have two interfaces in series. 

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