Nb-containing hematites Fe2−xNbxO3: The role of Nb5+ on the reactivity in presence of the H2O2 or ultraviolet light

A series of Nb-containing hematites, Fe2−xNbxO3 (%Nb = 0.00, 1.49, 5.00 and 9.24) was prepared using the conventional co-precipitation method. Mössbauer and temperature-programmed reduction (TPR) measurements suggested the formation of the crystalline phase with partial substitution of Fe3+ by Nb5+ in the structure. N2 adsorption/desorption revealed that the presence of Nb has a remarkable effect on the textural properties of the material with an increase in the BET surface area. The reactivity of Fe2−xNbxO3 was investigated using the oxidation of the methylene blue dye used as a model pollutant. The obtained results showed that the presence of Nb seems not to act directly promoting the H2O2 decomposition, but improving the dye oxidation. The analysis using the ESI-MS technique showed partial oxidation observed through different intermediates before the mineralization. This suggests the use of Nb-doped hematite as an efficient catalyst in degradation reactions in the presence of H2O2 or ultraviolet light.

Niobium was introduced in the hematite structure to produce an active heterogeneous Fenton system and also to improve the photocatalytic activity. The reactions in the presence of H2O2 or ultraviolet light were carried out using the organic dye methylene blue. Niobium shows interesting features for this system such as, ionic ray compatible with the Fe structural and the high reactivity.Figure optionsDownload as PowerPoint slide