Hydrothermal Synthesis and Photocatalytic Properties of Cobalt-Doped Tungsten Oxide

Hexagonal tungsten trioxide–base interstitial solid solutions of general formula Co x WO 3 , where 0.01 ≤ x ≤ 0.09, were prepared hydrothermally. The dopant homogeneity extent was found to depend on рН in the working solution. Interstitial solid solutions with the highest Co 2+ concentrations were formed at рН of 2.3. The Co x WO 3 samples with a fiber-like morphology with a fiber diameter of ca. 40 nm, which were prepared at рН of 2.3, had the highest specific surface area, equal to 38.6 m 2 /g. The key parameter for the stability of the Co x WO 3 crystal structure appeared to be ammonium ions residing in the hexagonal channels of the crystal structure. When tested as photocatalysts of 1,2,4-trichlorobenzene oxidation under the UV light, the prepared samples showed high chloroarene conversions and low selectivities to yield a wide range of organic compounds, including chlorine-free ones.