Side reactions in photocatalytic H2 production by overall water splitting

The inefficiency of photocatalytic overall water splitting is well documented and has been extensively studied. However, a crucial aspect of this process, the side reaction, has often been overlooked. In this study, we investigate the impact of side reactions on photocatalytic overall water splitting by monitoring factors such as dissolved oxygen, reactive oxygen species, and hydrogen peroxide. Further insights into the side reaction are obtained through the introduction of a platinum cocatalyst. Our findings reveal that dissolved oxygen significantly contributes to the side reaction by promoting the production of hydrogen peroxide. This byproduct is generated at the expense of electrons needed for the hydrogen evolution reaction, thereby reducing the overall efficiency of photocatalytic water splitting. This article aims to provide guidance on future research directions in the field of water splitting, with a particular emphasis on photocatalysis. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.