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Hematoporphyrin IX, H₂HMP, 8,13-bis(1-hydroxyethyl)-3,7,12,17-tetramethyl-21H,23H-porphine-2,18-dipropionic acid and protoporphyrin IX, H₂PP, 8,13-divinyl-3,7,12,17-tetramethyl-21H,23H-porphine-2,18-dipropionic acid were efficiently immobilized on niobium oxide grafted on a silica gel surface, SiO₂/Nb₂O₅, by the -COO–Nb bond formed between the porphyrin carboxyl groups and the grafted Nb₂O₅. These immobilized porphyrins, SiO₂/Nb₂O₅/H₂HMP and SiO₂/Nb₂O₅/H₂PP, were further reacted with Co(II) in dimethylformamide, resulting in SiO₂/Nb₂O₅/CoHMP and SiO₂/Nb₂O₅/CoPP metallated complexes. The UV-vis spectra of the solid materials showed changes of the Q-bands (a_2u → e_g transition) upon metallation, indicating that by incorporation of Co(II) in the porphyrin ring the local symmetry changed from D_2h to D_4h. These materials, when incorporated in carbon paste electrodes, presented the property of electrocatalyzing O₂ reduction. Rotating disk experiments were performed in order to estimate the number of electrons involved in the process. It was observed that, for both modified electrodes, O₂ was reduced to water in a four-electron process. Amperometric studies showed the potentiality of both modified electrodes as sensors for the determination of dissolved dioxygen. The response time was less than 3 s. A linear response for both systems was obtained between 2 and 12 ppm.

A simple procedure for one-step growing Nb₂O₅ hollow nanospheres and nanotubes was proposed. The final products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained hollow spheres present a polycrystal surface while the nanotubes possess single crystal walls. Moreover, the factors that could impact the product morphology and crystal structure were discussed, and the corresponding mechanism was proposed accordingly. The crystal structure and morphology of products can be easily tuned by adjusting the molar ratio of Nb/Ti used, which determines the amount of F^- ions existing in the reaction system. The as-obtained Nb₂O₅ hollow nanospheres and nanotubes may exhibit enhanced applications in a wide range of areas. Additionally, it is rational to expect that this simple method can be extended to systems of other inorganic materials with desired morphologies.

The development of new nanomaterials with controlled characteristics for nanophotonics is of great relevance. In this work, photonic crystals with reflectance at the wavelength of 690nm and the value of 28% were formed by porous-alumina-assisted-anodizing of system Al/Ta on Si wafer. By selecting improved anodizing modes of system Al/Nb on glass, the reflectance was increased to 42% at the wavelength of 340nm. This result shows the high promise of the proposed methods and in the future will significantly improve the result by trying two- or three-stage methods of porous-alumina-assisted-anodizing, nanoimprint stamps and optimization of the anodizing modes for any wavelengths.