Sputter -coated N-enriched mixed metal oxides (Ta₂O₅-Nb₂O₅-N) composite: A resilient solar driven photocatalyst for water purification

This study demonstrated the formation of N-enriched mixed metal oxides (Ta₂O₅-Nb₂O₅-N and Ta₂O₅-Nb₂O₅) thin film composites used as photocatalysts to degrade P-Rosaniline Hydrochloride (PRH-Dye) dye under solar radiation. By controlling the N gas flow rate during the sputtering process, the N concentration in the Ta₂O₅-Nb₂O₅-N composite is significantly included, and demonstrated by XPS and HRTEM analysis. With the help of XPS and HRTEM investigations, it was determined that the addition of N to Ta₂O₅-Nb₂O₅-N significantly enhances the active sites. The Ta-O-N bond (N 1 s and Ta 4p_3/2 spectra) was verified by the XPS spectra. Ta₂O₅-Nb₂O₅ was found to have a lattice interplanar distance (d-spacing) of 2.52, whereas Ta₂O₅-Nb₂O₅-N showed the 2.5 (620 planes). A sputter-coated Ta₂O₅-Nb₂O₅and Ta₂O₅-Nb₂O₅-N photocatalysts were prepared, and their photocatalytic activity was evaluated using PRH-Dye as a model pollutant under solar radiation by adding H₂O₂ (0.01 mol). The photocatalytic activity of the Ta₂O₅-Nb₂O₅-N composite was compared with TiO₂ (P-25) and Ta₂O₅-Nb₂O₅. Ta₂O₅-Nb₂O₅-N showed very high photocatalytic activity compared to Degussa P-25 TiO₂ and Ta₂O₅-Nb₂O₅ under solar radiation and confirmed the presence of N in Ta₂O₅-Nb₂O₅-N significantly increased the generation of ˙OH radicals (in pH 3, 7 and 9). With the use of LC/MS, the stable intermediates or metabolite created during the photooxidation of PRH-Dye were assessed. The results of this study will provide useful insights on how Ta₂O₅-Nb₂O₅-N influences the efficiency of water pollution remediation.