Heterogeneous redox catalysis at conducting polymer ultramicroelectrodes

The theoretical analysis of the steady state current response expected for a polymer modified ultramicroelectrode when the latter is operating under b atch amperometric conditions is discussed. In particular, the interplay bet ween the substrate reaction and diffusion within an electronically conducti ng polymer is examined. Six distinct limiting kinetic situations are develo ped and presented schematically in the form of a kinetic case diagram. It i s predicted that the reaction order for the steady state catalytic current response with respect to bulk substrate concentration, mediator concentrati on and electrode radius produces a distinct triplet of characteristic value s for each kinetically limiting situation.