Thermodynamics of photoinduced charge transfer in semiconductor particles

1 Thermodynamics of photoinduced charge transfer in semiconductor particles 

The Fermi energy or Fermi level, Ef, of a solid is that energy at which the probability of electronic energy level occupancy is exactly 0.5. Chemically, the Fermi energy corresponds to the electrochemical potential of electrons in the solid. At equilibrium, all electronically conducting materials in contact have the same Fermi energy. 

It can be shown that the Fermi energy of an electrolyte containing a redox pair is equal to the Nernst energy level associated with the redox pair [95,125], i.e., for the general redox couple 

The requirement is reversed for spontaneous electron transfer from electrolyte to solid. If the solid in question is a semiconductor, the location of the Fermi energy is given by either of the following expressions  

In the absence of kinetic complications, the interfacial charge transfer reactions that occur during photoelectrolytic processes at illuminated semi- 

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