The molecular basis for the behaviour of niobia species in oxidation reaction probed by theoretical calculations and experimental techniques

Abstract

This paper describes the preparation and use of a new class of materials based on synthetic niobia as catalysts in the oxidation of organic compounds in aqueous medium. The chemical reactions were carried out in the presence of hydrogen peroxide (H₂O₂). The material was characterized with X-ray diffraction, XPS and H₂-TPR (temperature-programmed reduction) measurements. The organic molecule methylene-blue was used in the decomposition study as a probe contaminant. The analysis using the ESI-MS technique showed complete oxidation observed through different intermediates. This suggests the use of niobia species as an efficient Fenton-like catalyst in degradation reactions. Theoretical quantum DFT calculations were carried out in order to understand the degradation mechanism.

Keywords:

• niobia
• Fenton-like mechanism
• DFT calculations
• ESI-MS

Acknowledgements

The authors are grateful to FAPEMIG and CNPq for financial support and CBMM for samples. We would also like to thank to CENAPAD-SP for the computational facilities.