A model for Co-operative electron transfer

Abstract

Co-operative electron transfer through an electron transfer chain or an electron exchanging molecular complex, which has recently been introduced as a new mechanism of (photo)electrocatalysis, but could not unequivocally be verified by applying the slaving principle, is demonstrated for a slightly extended model. It involves a non-linear kinetic step prior to the feedback on electron transfer rate constants. An electron transfer state is found which is characterized by a high degree of co-operation of individual processes and a drastic reduction of activation energies resulting in a high electron flux. Such a co-operative electron transfer mechanism may be considered to be a simple model describing biological multicentre catalysts (nitrogen fixation, sulphate reduction, oxygen evolution). Introduction of a cubic non-linearity into the model results in a co-operative bistability which may act as a switch between a low conducting and a high conducting electron transfer state.