Towards durable photocatalytic seawater splitting: design strategies and challenges

Photocatalytic seawater splitting (PSWS), which utilizes abundant solar and ocean resources, is one of the most promising technologies for sustainable hydrogen production. However, the complex composition of seawater significantly limits the durability and activity of photocatalysts. In this review, we first identify the primary factors that contribute to photocatalyst deactivation during PSWS, including chloride induced corrosion and loss of active sites, and light shielding caused by precipitation of metal cation salts. Focusing on the effects of ions in seawater, we then discuss strategies to enhance the durability of photocatalysts. In particular, surface hydroxyl group engineering is highlighted for its role in enabling ion selectivity. We explore how surface hydroxyl groups facilitate preferential adsorption of protons (H⁺) from seawater and summarize synthetic methods for developing photocatalysts with enriched surface hydroxyls. Additionally, we emphasize the importance of optimizing conditions for reactions involved in PSWS including multi-field coupling using semiconductor-based materials, which have unique advantages for improving performance in complex seawater environments.