Hierarchical SixFe1-xO nanostructures anchored on MgO for efficient visible-light-driven hydrogen production

Defect engineering and heterointerface engineering are recognized as efficient strategies for enhancing the activity of cost-effective photocatalysts toward sustainable hydrogen generation. In this work, earth-abundant Si x Fe 1-x O/MgO heterostructured nanocomposites were synthesized through a scalable solid-state route and systematically evaluated for visible-light-driven hydrogen evolution. Compositional tuning (x = 0.25–0.57) enabled precise control over defect concentration, and interfacial charge-transfer behavior. Among the prepared samples, the Si 0.57 Fe 0.43 O/MgO heterostructure exhibited the highest hydrogen evolution rate of 3190 μmol H 2 h -1 with an apparent quantum yield (AQY) of 2.97%, maintaining excellent stability over repeated cycles. The results revealed the coexistence of Fe 2+ /Fe 3+ states and abundant oxygen vacancies, which served as active defect centers facilitating charge separation and suppressing recombination. Theoretical study demonstrated the adsorption thermodynamics at the heterointerface are influenced by Fe d-orbital contributions near the Fermi level. This study provides a rational design strategy for developing noble-metal-free with high photocatalytic efficiency for solar-driven hydrogen production.