Electrochemical crystal double layer region

Jusys and Bruckenstein [84] have used electrochemical quartz crystal microbalance to study adsorption/desorption of perchlorate and perrhenate ions on a bare polycrystalline Au electrode. The change in the equivalent mass was undoubtedly assigned to the adsorption of both anions in the double-layer region of Au electrode. 

We shall restrict our consideration here to the simplest electrochemical case the electrical double layer, which is not complicated by charge transfer or by specific adsorption. At first glance it would seem that, if there is no change in mass and nothing happens in the bulk of the solution in which the electrode is immersed, the EQCM response should be zero. However, essentially all measurements show that in the double-layer region the frequency of the EQCM depends on potential. The effect is rather small—a few Hz for crystals with fundamental frequencies of 5-10 MHz. 

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