Hydrothermal Synthesis and Photocatalytic Properties of Iron-Doped Tungsten Oxide

Hexagonal h-WO₃-based substitutional solid solutions of general formula h-W_1–xFe_xO₃, where 0.01 ≤ x ≤ 0.06 were prepared by hydrothermal synthesis. The crystal lattice of the prepared h-W_1–xFe_xO₃ compounds is stabilized by \({\text{NH}}_{4}^{ + }\) ions in hexagonal channels. Quantum-chemical calculations showed that dopant iron ions replace cations in the tungsten sublattice, and are not intercalated into lattice channels. The dopant is not an independent participant in reactions involving h-W_1–xFe_xO₃, but only causes the reorganization of the near-Fermi states of the h-WO₃ matrix. The extent of the dopant homogeneity range of the solid solution is determined by the pH of the working solution. The h-W_0.94Fe_0.06O₃ prepared at pH 2.3 has the largest specific surface area, equal to 108 m²/g. Its photocatalytic activity in 1,2,4-trichlorobenzene (TCB) photodegradation is several times that of m-W_0.94Fe_0.06O₃.