In this article, we review our recent research efforts on the synthesis, crystallinity control, and photocatalysis of nanostructured titanium dioxide (TiO2) shells. First, we introduce several synthetic methods for preparing TiO2 shell structures using either template-free or template-assisted approaches. Several methods to change the structures from amorphous to crystalline and subsequently ways to enhance the crystallinity are then discussed, including those involving the “silica-protected calcination” and “partial etching and recalcination” strategies. We also discuss the photocatalytic applications of the TiO2 nanoshells and the methods for improving their catalytic activities. Finally, we conclude with a summary and our perspective on the further development of the nanostructured TiO2 shells. It is believed that more rational design and modification strategies such as well-controlled nonmetal doping, plasmonic metal decoration and the hybridization with other semiconducting materials will significantly enhance the photocatalytic efficiency of TiO2-based catalyst materials.

A modified polyol synthesis has been utilized to study the different structures obtained in the bimetallic system of platinum (Pt) and palladium (Pd). Some results are shown in this work. Thermal methods under refluxing, carrying on the reaction up to 285 ºC, have been assayed to reduce metallic salts using ethylene glycol (EG) as reducer and polyvinylpyrrolidone (PVP) as protective reagent of the formed bimetallic nanoparticles. The special core-shell structure has been observed in these bimetallic nanoparticles, whose synthesis was assisted by Ag, showing polyhedral shapes. The average diameter size of the core has been estimated at 10 nm, and the diameter size of the shell in 13 nm, consequently the thickness of the shell is around 1.5 nm. Nanoparticles were structurally characterized with transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) equipped with detector to generate high angle annular dark field (HAADF) images. This kind of structures have been studied and utilized to increase successfully the catalytic properties of monometallic nanoparticles of Pt or Pd according to other works. Here, the synthesis procedure is described; as the main results, several images are presented showing the obtained bimetallic core-shell structures and their fast Fourier transform (FFT), and also the size and the elemental analysis of the nanoparticles are reported, concluding that this synthesis method is very efficient for preparing bimetallic core shell structures.