A model for the current-voltage curve of photoexcited semiconductor electrodes

Abstract

A model to describe the behavior of photoexcited electrodes in an electrochemical cell is developed. In addition to the bulk semiconductor properties, the important parameters are a surface recombination parameter S_r and a surface electron transfer parameter S_t. It is the electron transfer process across the interface that leads to current in the external circuit. Using experimental curves for oxygen evolution at an n‐type TiO₂ electrode and Hall‐Shockley‐Read recombination to determine S_r, it is shown that the I‐V curve in anodic bias is controlled by the competition between S_r and S_t. The physical basis for S_t is discussed and experimental approaches to investigate surface reactions are suggested.