Photocatalytic water splitting over iron oxide nanoparticles intercalated in HTiNb(Ta)O₅ layered compounds

Nanosized iron oxide particles were intercalated into the interlayer of layered compounds HTiNb(Ta)O₅ by a successive ion-exchange reaction. The electronic and local coordination structures of iron oxide in the interlayer space of these proton-containing compounds were investigated by X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). The intercalated nanosized iron oxide was Fe₂O₃, which exhibited a high electron deficiency. Unlike in a previous report, Fe ₂O₃-intercalated layered compounds did not produce hydrogen from an aqueous methanol solution in a photocatalytic manner under visible light. Instead, the material produced a stoichiometric mixture of hydrogen and oxygen photocatalytically under UV irradiation and produced oxygen from an aqueous AgNO₃ solution photocatalytically under visible light.