ELECTRON-TRANSFER KINETICS OF REDOX REACTIONS AT THE SEMICONDUCTOR ELECTROLYTE CONTACT - A NEW APPROACH

The model used for electron-transfer kinetics between the electronic charge carriers of a semiconductor and the species of a redox couple in an electrolyte has been refined by taking into account the statistics of forming a reaction pair at the interface. Electron transfer within such a reaction pair is described by the semiclassical theory. A comparison is made between the electron transfer in the forward direction over a semiconductor-metal and a semiconductor-redox electrolyte Schottky barrier of equal height. The result indicates that electronic equilibrium between bulk and surface is maintained in the electrochemical system over the entire current voltage range. The rate of electron transfer via surface states is compared with the transfer via the band edge within the same model. Conditions that can favor the reaction path via surface states are specified.