Generalized Mott–Schottky Analysis of Photoelectrodes

Mott–Schottky analysis is a widely used technique for characterizing photoelectrodes that are critical to photoelectrochemical energy conversion. However, its validity depends on strict assumptions that are often overlooked, leading to potential inaccuracies in the interpretation of experimental data. In this study, we present an extended theoretical framework that overcomes the limitations of conventional Mott–Schottky analysis. This improved approach accounts for nonlinearities commonly observed in experimental data by considering the influence of the electrostatic potential in the Helmholtz layer. Reanalysis of literature data using this enhanced model demonstrates significant revisions in key parameters, including reductions in donor density by up to a factor of 5 and flat-band potential shifts of 0.1 V, while achieving a better fit to experimental observations. Importantly, the modified equation is consistent with a linear-conventional Mott–Schottky analysis for materials with low doping density. These refinements underscore the need for adopting this generalized Mott–Schottky analysis in the electrochemical characterization of energy materials.