Influence of Zinc Acetate Concentration on ZnO Growth on Anodized Nb2O5 Nanoporous Films and Photocatalytic Dye Degradation

In this study, Nb₂O₅-ZnO films were synthesized using a two-step process that involved growing hydrothermal ZnO microrods on the surface of anodized nanoporous Nb₂O₅. We present the morphological, structural, and optical properties of Nb₂O₅-ZnO films synthesized in hydrothermal solutions with varying concentrations of Zinc Acetate ranging from 0.01 to 0.25 M, as well as the photocatalytic performance of each sample. The results show that ZnO grew in the form of rods from 0.01 to 0.05 M and then began to form hexagonal prisms at 0.25 M molar concentration. The XRD patterns of the Nb₂O₅-ZnO films clearly show a dominant orthorhombic Nb₂O₅ phase as well as a ZnO phase with a hexagonal wurtzite structure. Another finding from this study is that as molar concentration increases, the band gap of the Nb₂O₅-ZnO film decreases from 3.077 to 3.017 eV. Owing to high surface area and porosity of the produced films, visible light-assisted photocatalytic activity of Methylene Blue solution was performed to examine the performance of the films on dye degradation. The obtained results confirmed that the sample Nb₂O₅-ZnO 0.05 M showed the highest photocatalytic activity, with almost 98.41% removal of Methylene Blue after 180 min under the light exposure. The excellent photocatalytic performance of Nb₂O₅-ZnO 0.05M is expected due to the high effective surface area for Methylene Blue reaction, good crystallinity, high absorption, and low band gap behaviour of the sample. Furthermore, the couple layer can significantly reduce the recombination rate of photogenerated electron-hole pairs while also compensating for the disadvantages of the individual components, resulting in a synergistic effect of efficient charge separation and improved photostability.