Theoretical Studies of Electron Transfer and Electron Localization at the Semiconductor−Liquid Interface

Abstract

We present new models and simulations of electron transfer (ET) at the semiconductor−liquid interface (SLI). The simulations are of a “first principles” molecular dynamics type and therefore incorporate electronic structure calculations. An In(H2O)6 2+/3+ redox species, water, and InP semiconductor system are focused on. We discuss the problem of electron localization at this interface, especially as it relates to ET. The study allows the mechanism of the ET process to be analyzed. Rate constant calculations are performed with the dynamics of the entire system incorporated. We apparently present the first calculation of electron transfer coupling matrix elements for the SLI.

On the theory of electron transfer reactions at semiconductor electrode/liquid interfaces

“…It would be useful therefore to study the two semiconductor systems with the same molecular species, if possible. 9,16 Although the density of bulk states of the InP conduction band is large, of the order of 10 17 cm Ϫ3 , the decay length of their coupling to the molecule of about 1 Å yields an effective surface density of states of the conduction band of the order of only 10 9 cm Ϫ2 . We note further that in a free-electron model a surface state has a wave function which can be expressed as…”

“…Smith and Nozik 13,14 studied the semiconductor/liquid interfacial adiabatic electron transfer reactions by extending Schmickler's treatment 15 for metal/ liquid electron transfer reactions, choosing an Anderson-type Hamiltonian, and by molecular dynamic calculations. 16 In the present paper, the electron transfer reactions at semiconductor/liquid interfaces are treated nonadiabatically. Extended-Hückel calculations are performed to estimate the electronic coupling between the donor/acceptor level of the redox agent and the solid electronic states of the semiconductor.…”

Theory of ultrafast photoinduced heterogeneous electron transfer: Decay of vibrational coherence into a finite electronic–vibrational quasicontinuum

“…One can use for instance the functional form from a one-dimensional ͑1D͒ chain of atoms for compound semiconductors with a constant coupling for the molecular excited state at the end of the semi-infinite chain 34 or where the coupling is also varying. 23 However, for purposes of illustrating the general physics, the simple case that was considered in the pure electronic QC will be taken up namely…”

Comparison of the photoelectrochemical oxidation of methanol on rutile TiO2 (001) and (100) single crystal faces studied by intensity modulated photocurrent spectroscopy

“…Details of many photoelectrochemical reactions in general have been successfully investigated using dynamic photoelectrochemical methods. 8 Photocurrent transient methods [9][10][11][12][13][14][15] and intensity modulated photocurrent spectroscopy (IMPS), 8,10,[16][17][18][19][20][21][22] where the working electrode is illuminated with sinusoidally modulated light, have been used for this purpose in particular. These methods can be employed to measure the rate constants of charge transfer and recombination processes occurring at the semiconductor/electrolyte interfaces.…”