Oxy-Sulfide Semiconductors for Hydrogen Production from Pure Water: Materials Design, Performance, and Stability.

Abstract

Advancing toward sustainable hydrogen production requires catalytic materials that are efficient, stable, and composed of earth-abundant elements. Oxy-sulfides have emerged as promising candidates because they are poised to combine the structural strength of oxide semiconductors with the narrower band gap energies, and enhanced electronic conductivity characteristic of sulfides. This review summarizes recent progress in the use of oxy-sulfides as both photocatalysts and electrocatalysts for H2 production from pure water, with emphasis on mixed-anion electronic structure, band-edge engineering, and charge-carrier dynamics. Particular attention is given to layered titanate oxy-sulfides that enable visible-light-driven overall water splitting. Strategies such as anion regulation, heterostructure formation, and defect engineering are discussed in relation to their influence on catalytic activity, carrier lifetimes, and stability. The review also examines key degradation pathways and this includes photocorrosion, surface reconstruction, and compositional drift in addition to a summary of emerging approaches to mitigate these effects. Despite substantial progress, solar-to-hydrogen efficiencies (STH) in pure-water remain well below levels required for practical deployment, highlighting the need for further improvements in light harvesting, charge separation, and long-term durability. Future research directions involving operando characterization, computationally guided materials design, and scalable synthesis are discussed.