Hydrogen adsorption on Ru-decorated (8,0) zigzag single-walled carbon nanotube (SWCNT) was studied using density functional theory (DFT). Several decoration sites on the CNT surface were investigated before atomic or molecular hydrogen adsorption. The most stable location for a single Ru atom is above the hollow site, with an adsorption energy of E ads (Ru) = −2.133 eV. Ru decoration increases hydrogen adsorption energy nearly 46% compared to pristine CNT. When a hydrogen molecule is considered on Ru/SWCNT its adsorption is dissociative with an E ads (H 2 ) = −0.697 eV. The Ru-decorated SWCNT systems exhibit magnetic properties. Density of states (DOS) and overlap population density of states (OPDOS) were computed in order to study the evolution of the chemical bonding. C−C bonds interact with Ru and are weakened after adsorption. Strong Ru−H bonds are formed during hydrogen adsorption process at expenses of C−Ru bonds. The mains interactions include the Ru 5p z and 4d z 2 and C 2p z bands.

A systematic spin-polarized density functional theory (DFT) study of hydrogen interaction with pristine and Rh-decorated zigzag (8,0) single-walled carbon nanotubes (SWCNTs) was performed. The most stable decoration site for Rh atoms as well as atomic and molecular hydrogen adsorption inside and outside the SWCNT was studied. Hydrogen adsorption energy in Rh-decorated SWCNTs was improved compared to that of pristine nanotubes. In addition, Rh-decorated SWCNT systems present a magnetic moment. Density of states and work function (WF) were computed to study the bonding evolution and electronic structure. When hydrogen is considered on Rh-SWCNT and pristine SWCNT, the WF increased while band gap decreased compared to that of pristine SWCNT.

Pure decahedral anatase TiO(2) particles with high content of reactive {001} facets were obtained from titanium(IV) tetrachloride (TiCl(4)) using a microemulsions droplet system at specific conditions as chemical microreactor. The product was systematically characterized by X-ray diffraction, field-emission scanning and transmission electron microscopy (FE-SEM, TEM), N(2) adsorption-desorption isotherms, FT-IR and UV-vis spectroscopy, and photoluminescence studies. The obtained cuboids around 90 nm in size have a uniform and dense surface morphology with a BET specific surface area of 11.91 m(2) g(-1) and a band gap energy (3.18 eV) slightly inferior to the anatase dominated by the less-reactive {101} surface (3.20 eV). The presence of reactive facets on titania anatase favors the biomimetic growth of amorphous tricalcium phosphate after the first day of immersion in simulated human plasma. The results presented here can facilitate and improve the integration of anchored implants and enhance the biological responses to the soft tissues.

Silica-based nanomaterials are of great interest because of their potential applications in constructing electronic and optoelectronic nanodevices. Especially significant are those that combine the properties of photonic crystal with a fibrous semiconductor structure. Here we report the use of microemulsion droplet systems as a simple and controllable route for the synthesis of 3D opals materials with an unusual fibrous microstructure similar to those that exist in nature. By this method, we demonstrate the creation of very long fibrils of 30-50 nm diameter and more than 20 μm length showing simultaneous short and long wavelength light emissions and band gap values (5.50 and 4.41 eV) comparable to those obtained for silicon-based metal oxide semiconductors.

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DFT calculations were used to study hydrogen desorption energy in a set of pure, Nb-or Zr-doped systems, containing vacancy-like defects and a MgH 2 (110) defect-free surface. The preferential location site for dopants was determined by means of occupation energy analysis. Both transition metal atoms (Nb and Zr) preferred interstitial sites. The effect of vacancies in the systems was also considered. MgH 2 with a Nb interstitial atom and MgH 2 with a Zr interstitial atom containing a Mg vacancy modifies the surface geometry and weakens the Mg−H bonds thus easing the H desorption process.

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