Photocatalytic Degradation of Methylene Blue Dye by Electrospun Binary and Ternary Zinc and Titanium Oxide Nanofibers

Synthetic dyes, dispersed in water, have harmful effects on human health and the environment. In this work, Ti and/or Zn oxide nanofibers (NFs) with engineered architecture and surface were produced via electrospinning followed by calcination. Calcination and subsequent cooling were operated at fast rates to generate porous NFs with capture centers to reduce the recombination rate of the photogenerated charges. After morphological and microstructural characterisation, the NFs were comparatively evaluated as photocatalysts for the removal of methylene blue from water under UV irradiation. The higher band gap and lower crystallinity were responsible for the lower photocatalytic activity of the ternary oxides (ZnTiO3 and Zn2TiO4) towards the degradation of the dye. The optimal loads of the highly performing binary oxides were determined. By using 0.66 mg mL−1 wurtzite ZnO for the discoloration of an aqueous solution with a dye concentration of 15 µM, a higher rate constant (7.94 × 10−2 min−1) than previously reported was obtained. The optimal load for anatase TiO2 was lower (0.33 mg mL−1). The corresponding rate constant (1.12 × 10−1 min−1) exceeds the values reported for the commonly used P25–TiO2 benchmark. The catalyst can be reused twice without any regeneration treatment, with 5.2% and 18.7% activity decrease after the second and third use, respectively.

Synthesis, Optical Properties and Applications of Ternary Oxide Nanoparticles by a Microwave Technique

Nanocrystal preparation is in high demand due to the development of nanodevices. Nanostructures or microstructures of binary oxides such as TiO2, ZnO, and Al2O3 have been extensively prepared and studied. Synthesis of ternary oxide nanomaterials with controlled structures, morphologies, and sizes are of interest due to their potential applications in nanodevices caused by tunable energy level, bandgap, and structure. In this work, a solution-based method is used to prepare CaWO4 and LaPO4 ternary oxide nanomaterials by microwave technique. Controlled sizes and morphologies including nanorods and microspheres are synthesized by the microwave method, which is believed to be a facile and low-cost technique for the synthesis of ternary oxide nanomaterials. Furthermore, the (relatively) quick process enables high efficiency of the production. The structural and optical properties of the prepared nanomaterials are also investigated in this work. This work benefits nanomaterial synthesis for nanomanufacturing and applications in lighting and photodynamic activations as well as optical storage.