Developing and Understanding BiFeO3 Photoelectrodes for Solar Water Splitting

Abstract

Hydrogen production by photoelectrochemical water splitting is a challenging and exciting research topic that continues to receive much attention as it is a promising option for meeting the global energy demand. For this technology to compete with fossil fuels, a solar-to-hydrogen (STH) efficiency above 10% must be achieved using an inexpensive and durable photoelectrochemical cell (PEC). Accordingly, our group has been investigating oxide-based photoelectrodes that can be produced via practical solution-based syntheses using inexpensive raw materials. We are specifically interested in developing ternary oxides, which provide more opportunities to tune the composition and atomic/electronic structures of the photoelectrode materials relative to their corresponding binary oxides. In this presentation, the synthesis and investigation of BiFeO3 photoelectrodes will be discussed. BiFeO3 has a bandgap of ~2.2 eV and appropriate band positions for water splitting; however, it has not been extensively studied for photoelectrochemical applications. BiFeO3 has previously shown both n-type and p-type behavior, meaning it can serve as either a photoanode for water oxidation or photocathode for water reduction, respectively. Here, we will first introduce electrochemical methods to prepare high-quality n-type and p-type BiFeO3 films. We will then discuss the photoelectrochemical properties of the resulting films and present strategies to further optimize the performance of BiFeO3 as both a photoanode and photocathode for use in a water-splitting PEC.