Temperature dependence of the transfer coefficient of simple electrochemical redox reactions due to slow solvent dynamics

It is shown that for simple electrochemical redox reactions in which both outer- and inner-sphere modes are reorganized, the transfer coefficient alpha may decrease with increasing temperature if the solvent dynamics along the outer-sphere coordinate is sufficiently slow. A similar trend is observed for the activation energy, The effect is due to a change in the most effective reaction path with temperature and is intimately related to the phenomenon of saddle-point avoidance. It is also shown that the effect enhances the potential dependence of the transfer coefficient.