Innovative sulfur-based photocatalysts for seawater splitting: Synthesis strategies, engineering advances, and prospective pathways for sustainable hydrogen production

While hydrogen production through pure water splitting remains a key focus in solar hydrogen research, photocatalytic seawater splitting presents a more sustainable alternative, better aligned with global development goals amid increasing freshwater scarcity. Nevertheless, the deactivation of the photocatalyst by the corrosion of various ions present in seawater, as well as the chloride ions' redox side reaction, limits the practical use of the photocatalytic seawater splitting process. In this context, sulfur has emerged as a crucial component in photocatalytic composites for seawater splitting, owing to its unique chemical properties. It acts as a chlorine-repulsive agent, effectively suppressing chloride ion oxidation, which mitigates corrosion, enhances structural stability, and significantly improves overall photocatalytic performance in saline environments. This review offers a thorough explanation of the basic ideas of solar-driven seawater splitting, delves into various synthesis strategies, and explores recent advancements in sulfur-based composites for efficient hydrogen generation using seawater. Optimizing synthesis techniques and incorporating strategies like doping, cocatalyst, and heterojunctions significantly enhance the performance of sulfur-based photocatalysts for seawater splitting. Future advances include integrating AI-guided material discovery, sustainable use of industrial sulfur waste, and precise control of sacrificial agents to ensure long-term efficiency and stability.