Capacitive current, chronocoulometry

Introduction Anions have a strong tendency to adsorb specifically at metal surfaces, for example, to estabKsh a direct bond with the electrode by partial loss of their hydration shell. As a consequence of the contact with the electrode, the ionic character of the anions is markedly reduced, resulting in a higher surface concentration than in case of nonspecific adsorption. This effect was first observed in double-layer studies on mercury [229, 230] and later confirmed and studied in detail on single-crystal solid electrodes [231-234]. Specifically adsorbed anions can form various types of ordered structures, either more open (cf. sulfate on Au(hld) [235, 236]) or close-packed as reported for halides on different solid electrodes [21]. Cyclic current-potential curves often reveal sharp current peaks, indicative of phase transitions within the anionic adlayers and hence of the existence of ordered phases [21, 237]. Thermodynamic data of specific anion adsorption was obtained in surface tension studies (on mercury only [229,238-240]), capacitance measurements [231-233], cyclic voltammetry, and chronocoulometry [234]. As an... 

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