Zinc oxide is considered an outstanding photocatalyst candidate, but its low photo-corrosion resistance is a problem to be solved. In the ZnO-ZnS core-shell structure, ZnS acts as a protective layer for the ZnO core, and thus, it can enhance stability and long-term performance. The ZnO-ZnS core-shell structure is synthesized into various nanoscale morphologies with high specific surface areas to improve photocatalytic efficiency. However, they are easily agglomerated and are hard to separate from reaction media. In this study, micro-sized bumpy spheres of ZnO-ZnS core-shell structure were prepared via facile chemical transformation of as-prepared ZnO. After sulfurization of the ZnO template, it was confirmed through SEM, TEM, EDS, and XPS analysis that a uniform ZnS shell layer was formed without significant change in the initial ZnO morphology. The ZnO-ZnS core-shell microsphere has shown superior efficiency and stability in the photocatalytic degradation of Rhodamine B compared with pristine ZnO microspheres

Black TiO ₂nanofibers have recently emerged as a promising material that has both advantages of black metal oxide and one-dimensional nanostructure. However, current reduction-based synthesis approaches are not compatible with practical applications because these processes require high process costs, complicated processes, and sophisticated control. Therefore, it is still necessary to develop a simple and facile method that can easily introduce atomic defects during the synthesis process. This work suggests an electrospinning process with an antioxidant and subsequent calcination process for the facile synthesis of black TiO ₂ nanofibers. The synthesized black TiO ₂ nanofiber has an average diameter of 50.3 nm and a rutile structure. Moreover, this nanofiber represented a noticeable black color and a bandgap of 2.67 eV, clearly demonstrating the bandgap narrowing by the introduced atomic defects.

The nano-sized Y2O3 dispersed W composite powder is prepared by ultrasonic spray pyrolysis of a tungsten precursor using ammonium metatungstate hydrate and a polymer addition solution method using Y-nitrate. XRD analysis for calcined powder showed the formation of WO2 phase by partial oxidation of W powder during calcination in air. The TEM and phase analysis for further hydrogen reduction of calcined powder mixture exhibited that the W powder with a uniform distribution of Y2O3 nanoparticles can be successfully produced. These results indicate that the wet chemical method combined with spray pyrolysis and polymer solution is a promising way to synthesis the W-based composites with homogeneous dispersion of fine oxide particles.

An optimum route to synthesis the W-based composite powders with homogeneous dispersion of oxide nanoparticles was investigated. The La2O3 dispersed W powder was synthesized by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and lanthanum nitrate. The dispersion of Y2O3 nanoparticles in W- La2O3 powder was carried out by a polymer addition solution method using yttrium nitrate. XPS and TEM analyses for the composite powder showed that the nano-sized La2O3 and Y2O3 particles were well distributed in W powder. This study suggests that the combination processing of ultrasonic spray pyrolysis and polymeric additive solution is a promising way to synthesis W-based composite powders.