The present monograph attempts to unify these diverse and exciting new developments within a common framework. First, the physical principles underlying heterogenous electron-transfer processes are outlined in a concise way and are compared to the homogeneous counterpart. This analysis includes the notion of the Fermi level in liquids and solids as well as the distribution of electronic energy levels in solids and liquids. A comparison is made between the salient kinetic features of homogeneous and heterogeneous electron transfer reactions. This establishes the basis for the subsequent...