Hierarchical MgxFeyO1−x−y/ZrO2 heterostructures for efficient solar water splitting

Photocatalytic water splitting using earth-abundant materials represents a sustainable pathway for clean hydrogen production. In particular, noble metal-free multivalent oxides with engineered oxygen vacancies exhibit superior photocatalytic hydrogen evolution owing to enhanced charge separation. Further optimization of defect-mediated photocatalytic activity remains crucial for water splitting. In this study, oxygen-deficient Mg x Fe y O 1-x-y /ZrO 2 heterostructures were synthesized and studied in the overall water splitting under the visible light irradiation. The contents of x (0.10–0.50) and y (0.05–0.35) were systematically varied to optimize the defect chemistry, electronic structure, and interfacial charge-transfer kinetics. The most active photocatalyst was identified as the Mg 0.30 Fe 0.17 O 0.53 /ZrO 2 heterostructure with the production of 1051 μmolg −1 h −1 and an apparent quantum yield (AQY) of 6.43%. The high activity could be attributed to defect-mediated electronic interactions and the partial reduction of Mg 2+ , Fe 2+ /Fe 3+ , and Zr 4+ species which facilitates charge transfer and enhances photocatalytic performance. The findings showed that the catalyst was recyclable with different water sources. This study provided valuable insights into interfacial design strategies for scalable oxide heterostructures aimed at sustainable solar hydrogen production.