Small signal (local) analysis of electrocatalytic reaction. Pole-zero approach

The small signal response of a model electrocatalytic reaction is analysed following the author's earlier analysis of non-linear, large signal responses of this reaction under steady-state conditions. The kinetic parameters assumed generated peculiarities in large signal responses such as multiple steady states with hystereses and non-monotonic relations of surface coverage versus potential. The corresponding potential dependences of the electrode immittance parameters were calculated: high frequency limit (modulus), zero and pole of the immittance. Their advantage for the characterisation of small signal responses consists in a direct definition of the system's stability and the distinction between the 'capacitive' and the 'inductive' character of the electrode immittance. Equality of the kinetic parameters of constituent reactions results in equal values of zero and pole and hence in a purely resistive character of the electrocatalytic reaction immittance. (C) 1999 Elsevier Science S.A. All rights reserved.