Spectral Dependencies of the Quantum Yield of Photochemical Processes on the Surface of Nano/Micro-Particulates of Wide-Band-Gap Metal Oxides. IV. Theoretical Modeling of the Activity and Selectivity of Semiconductor Photocatalysts with Inclusion of a Subsurface Electric Field in the Space Charge Region

Abstract

In an earlier study (Emeline, A. V.; Ryabchuk, V. K.; Serpone, N. J. Phys. Chem. B 1999, 103, 1316) we reported the solution to the continuity equation in which we neglected electric field effects and obtained expressions for the concentrations of the charge carriers at the surface (ns), for the quantum yield (Φ) of a photochemical surface redox reaction, together with an expression for the selectivity of the photocatalyst. Various considerations led us to infer and predict wavelength-dependent phenomena (quantum yields and selectivity), which were later confirmed by experimental results (Emeline, A. V.; Serpone, N. J. Phys. Chem. B 2002, 106, 12221). In this article we revisit the continuity equation but include a subsurface electric field (E) in the space charge region of the semiconductor (or dielectric) photocatalyst to assess the effect that the electric field has on the activity and selectivity of the photocatalyst. The solution to the continuity equation yields very complex expressions for ns and f...