Photoelectrochemical Methods for Flat Band Potential Estimation: Case Studies of ZnO Nanorods and TiO₂ Compact Films

Abstract

Semiconductor materials play a major role in the use of solar energy. ZnO and TiO2-based nanomaterials have been broadly used in photocatalytic applications, such as water splitting and environmental remediation. In order to determine the thermodynamic feasibility in a specific application, it’s important to determine the electronic band structure of these materials. This determination of the energetics in the semiconductor can be conducted from different approaches, usually being determined by the bandgap and conduction band edge first. The bandgap determination is made through well-defined and standardized processes, unlike the conduction band, where the discrepancy is found between the values reported by different authors under the same conditions. In this article a comparison is made between the Mott-Schottky, photocurrent onset potential, and open-circuit potential methods, as techniques of determining the flat band potential, taking as case studies the two semiconductor materials mentioned above. This comparison is followed by a discussion of the difficulties that may arise during experimentation and the possible difference between the values reported by each method.

Photoelectrochemical Methods for the Determination of the Flat-Band Potential in Semiconducting Photocatalysts: A Comparison Study

“…The described methods have been developed many years ago, but still little information can be found in the literature on their comparison and application for characterization of different photocatalysts. − It was our motivation to improve this situation and increase the number of valid examples.…”