Nanostructured niobium oxide synthetized by a new route using hydrothermal treatment: High efficiency in oxidation reactions

•Nanostructured niobium oxides were synthesized by hydrothermal treatment.•Oxalic acid or H2O2 as structure-directing agents resulted in materials with different properties.•These new catalysts demonstrated great performance in decomposition of methylene blue (MB).•The best result for Fenton-like reactions indicated the removal of 80% of MB in just 30 min using the Nb2O5-HP.•The photocatalysis tests using UV light irradiation provided the removal of up to 86% of MB after 5 h using the Nb2O5-OX catalyst.

Nanostructured niobium oxides were synthesized by hydrothermal treatment using an amorphous Nb2O5 as precursor. The modification by hydrothermal treatment in the presence of oxalic acid or hydrogen peroxide resulted in versatile catalysts with many different properties verified by several characterization techniques. XRD analysis demonstrated the crystallinity increase. Significant morphological changes were observed by TEM, being possible to observe the presence of nanorods for the material treated with oxalic acid and nanospheres for the material treated in the presence of H2O2. Modifications in the porous structure were also observed, as well as the increase in BET specific area. This significant difference compared to precursor resulted in catalysts with higher performance than Nb2O5 in decomposition of methylene blue dye (MB) by heterogeneous fenton-like reactions and photocatalysis under UV light irradiation.

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