Photoelectrochemical Kinetics [chapter]

John O'M. Bockris, Shahed U. M. Khan
1979 Quantum Electrochemistry  
The phenomenology and defects in former models are presented. A model for obtaining the current-potential and current-frequency relation is set up. The interaction energy of a photoelectron with a molecule adsorbed on the electrode is obtained by considering the Coulomb interaction between the electron and the -l-ve and -ve centres of the water dipole. Coulomb and Born interactions are accounted for. The barrier height is evaluated in terms of these potential energies. The equation for the
more » ... uation for the current in photoemission accounts for the reflective properties of the metal, electron-phonon and electron-electron scattering, the excitation probability from photon-electron interactions, the probability of barrier penetration and the presence of two kinds of acceptor states in solution. The equation is evaluated quantitatively and gives an absolute value of the photocurrent. It shows that (photo-current)215 should be linear with the electrode potential. The threshold energy evaluated for Hg is in fair agreement with experiment. The ability of the equation to represent the 5/2 law is insensitive to the change of barrier parameters. The photo-current is non-Tafelian because the incident photons in the range of >3.0 eV lift the photo-electrons to energies above the ground state of the H30+ vibrationalrotational states: no distribution law for their presence is effective. The electrons of the dark current emit at lower energies and are predominently accepted by the (exponentially distributed) H30+ states, and this fact leads to Tafel-like relations.
doi:10.1007/978-1-4684-2493-5_12 fatcat:urmp2fb3fnan7dgpinkzhlnzhq