Systems Developing an Optimal Strategy for Electrocatalysis

Microheterogeneous Systems Developing an Optimal Strategy for Electrocatalysis 

We complete this section by discussing some implications for electrocatalysis and attempting to determine which case represents the optimum strategy for using polymer-bound dispersions of microparticles for electrocatalytic applications. 

Secondly we consider the microcatalyst-loaded ionomer or redox polymer system. We can again identify an optimum strategy. We immediately reject all cases where the current response depends on the concentration of the mediator, since unless the solubility of the mediator is limited, we can presumably increase the mediator-loading. This leaves Cases 1, 5, and possibly 6 (Figs. 2.46 and 2.47). In Cases 5 and 6 only a fraction of the catalyst particles are used, since the substrate does not penetrate the entire film we therefore reject these two cases. Thus we are left with Case 1, where the reaction occurs throughout the entire layer at a rate controlled by the spherical diffusion of the reactant in each catalytic particle. This represents the optimum strategy for this class of microheterogeneous system. In this situation the rate is enhanced by 

Chapter 2 discusses various theoretical models of polymer-based electrocatalytic systems. The discussion concentrated on an analysis of the steady-state current response. Time-dependent current responses are not considered. We have shown that the response of polymer-based electrocatalytic systems can be quantified in terms of very simple theoretical models. These models yield on analysis simple expressions for the current response involving experimentally quantifable parameters, such as layer thickness, catalyst-loading, and electrode potential. Determining reaction orders with respect to the latter parameter enables us to identify the kinetic case unambigously. Furthermore we have shown that kinetics can be conveniently represented in terms of pictorial case diagrams, which can be used in mechanistic diagnosis. 

The author wishes to acknowledge grant support from the CEC science program, the British Council, and EOLAS. Collaboration with Professor Philip Bartlett on the theoretical analysis of micro-heterogeneous systems over a number of years is also gratefully acknowledged. 

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