AC‐Impedanzmessungen an relativ dünnen Sperrschichtfilmen im Frequenzbereich 5·10‐3 Hz ⩽ f ⩽ 104 Hz im System polykristallines reines Al/0.16 M NH4‐tartrat bei pH 5‐7 im Potentialbereich ‐900 mV ⩽ EH ⩽ 400 mV zeigen, daß derartige Messungen eine wirksame Möglichkeit darstellen, um Informationen zu den Eigenschaften und der Kinetik passivierter Phasengrenzen zu erhalten.

Der elektrokatalytische Einfluß einer underpotential deposition (UPD) von Bi auf die kathodische Reduktion von O2 (O2 + 2H+ + 2e‐→ H2O2) und H2O2 (H2O2 + 2 H+ + 2e‐→ 2 H2O) wurde an poly‐ und monokristallinen (111)‐ und (100)‐Au‐Elektroden in 0.5 M HClO4 untersucht.

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ChemInform Abstract have been investigated in solutions containing perchlorate, acetate, or chloride (pH 1.5-3.55) by voltammetric and complex potential controlled perturbation techniques. The underpotential deposition of Pb on Cu(111) is found to be highly irreversible and to be dependent on pH, the electrical history of the metal-electrolyte interface, and the anions present. A critical threshold potential for thecathodic monolayer formation is revealed. The observed nucleation like behavior is interpreted in terms of a negative 2-D nucleation within a preformed surface layer consisting of oxygen-containing species.

ChemInform Abstract are carried out for the first time in the system YBa2Cu3O7-δ/RbAg4I5 by using a two-probe polarization technique under potentiostatic control. The results demonstrate clearly that precise EIS measurements can be performed down to temp. as low s 19 K with solid electrolytes (SE) of sufficient ionic conductivity and that valuable information on the extraordinary charge transfer behavior and the double layer capacity at HTSC/SE interfaces as well on the intrinsic properties of the electrolyte used can be obtained. In articular, it is found that the superconducting transition at Tc leads to a structural change of the electrochemical double layer and an enhancement of the charge transfer kinetics of the Faradaic electrode reaction.