Fundamental Principles of Semiconductor/Electrolyte Junctions

Abstract

This chapter describes the equilibrium and non-equilibrium characteristics of semiconductor electrodes immersed in electrolyte solutions. The intent is to build the reader’s intuition on how to use and design semiconductor photoelectrodes for effecting purposeful chemistry. The text illustrates how the kinetic details of charge transfer processes affect the concentrations of charge carriers in the semiconductor, thereby influencing experimental observables (e.g., current, potential). A brief historical summary of major ideas in the field is presented to help readers appreciate the development of models for heterogeneous charge transfer at semiconductor/solution interfaces. The Marcus and Gerischer formalisms are described, including predictions that have been verified and those that are still to be evaluated. These topics are intended to provide more explicit descriptions of key features of semiconductor photoelectrode responses that may not be intuitive and to distill key concepts to contextualize knowledge gaps and opportunities in the field.