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First-principles calculations are employed to explore and rationalize the potentialities of MoS 2 and WS 2 armchair nanotubes for Li and Mg ion battery applications. A comparison with the reported values for Li insertion in TiS 2 and MoS 2 nanotubes shows that WS 2 and MoS 2 nanotubes presented enhanced ion mobility. Especially for MoS 2 , the Li mobility is 4 times faster than in TiS 2 nanotubes. On the other hand, analysis of the Mg diffusion properties suggests that WS 2 nanotubes would be a better option, with ion mobility 3 times faster in relation to MoS 2 nanotubes. In terms of mobility, the Mg intercalation in WS 2 and MoS 2 nanotubes shows remarkable properties in comparison with Li insertion. Although it seems that Li and Mg insertion in WS 2 and MoS 2 nanotubes will be thermodynamically unstable, it is expected that the combination of nanotubes and high voltage electrode materials will increase the ion stability while keeping the faster ion mobility. Therefore, our results suggest high ion mobility at the surface of MoS 2 and WS 2 and support the potential application of the use of such systems as additive electrode materials for high-rate battery applications.

First-principles calculations based on the density functional theory (DFT) were applied to study the H2 adsorption on Au@Pd NP (core@shell icosahedral bimetallic nanoparticle). The calculations indicate that, for almost all adsorption sites, there is no energy barrier for H2 dissociation at the surface of Au@Pd NP, and the H2 molecule spontaneously dissociates. The only exceptions are the case of atop from edge (AE) and atop from vertex (AV) sites, where there is no dissociation at all. Looking at the adsorption energies, dissociated cases are 1.3 eV more stable than nondissociated cases. The work function (WF) values associated with NP with H2 adsorbed are lower than that obtained in the case of the Pd/Au(111) surface. When H2 is dissociated on the NP or surface, the WF increases, while in the nondissociated case it decreases. We also considered the changes in hydrogen adsorption and dissociation in mixed shell NP structures. The atomic H penetration was also studied for Au@Pd NP. Hydrogen adsorption on both Au@Pd NP and Pd/Au(111) surface systems leads to a slight shift of Pd’s d states to lower energies, while the s and p states are almost unaffected. A higher hybridization between Pd and H is detected in the NP case. Each H atom of the H2 molecule adsorbed on the NP becomes negatively charged. It seems that the charge transference occurs toward the NP. The bond order on orbital population analysis indicates no bond for H–H and a decrease in the metal–metal bond while a Pd–H bond is formed.

The use of ultraviolet (UV) and blue irradiation to sterilize surfaces is well established, but commercial applications would be enhanced if the light source is replaced with ambient light. In this paper, it is shown that nanofibers can be explored as an alternative methodology to UV and blue irradiation for bacterial inactivation. It is demonstrated that this is indeed possible using spun nanofibers of poly­[lactic-co-(glycolic acid)] (PLGA). This work shows that PLGA spun scaffolds can promote photoinactivation of Staphylococcus aureus and Escherichia coli bacteria with ambient light or with laser irradiation at 630 nm. With the optimized scaffold composition of PLGA85:15 nanofibers, the minimum intensity required to kill the bacteria is much lower than in antimicrobial blue light applications. The enhanced effect introduced by PLGA scaffolds is due to their nanofiber structures since PLGA spun nanofibers were able to inactivate both S. aureus and E. coli bacteria, but cast films had no effect. These findings pave the way for an entirely different method to sterilize surfaces, which is less costly and environmentally friendly than current procedures. In addition, the scaffolds could also be used in cancer treatment with fewer side effects since photosensitizers are not required.

In this work, the adsorption of hydrogen, oxygen and hydroxyl on metallic thin films is studied through first-principles calculations. We explore how the structural and electronic properties of palladium, platinum and gold thin films change with respect to the type of substrate. As a major result we find that Pd/Au(111) and Pt/Au(111) thin films present enhanced adsorption properties for H, O and OH. This improvement is a result of the induced tensile strain on the film due to the misfit between the lattice parameters of the film and the substrate. For these systems, the tensile strain results in a shift of the d-band center position towards to the Fermi level, with implications for the enhancement of adsorption properties. Our results suggest that the location of the unadsorbed d-band center for Pd/Au(111), Pt/Au(111) and Au thin films is a good parameter to predict the reactivity between these surfaces and H, O and OH. However, when considering different numbers of atomic monolayers, changes in adsorption energy are observed and there is no correlation for Pd/Au(111) and Au/Pt(111) films. For Pd/Pt(111) and Pt/Pd(111) films the difference between lattice parameters is relatively small, and no correlation is found, since no considerable strain is induced. In addition, our results support that a compressive strain will always lead to weaker adsorption. We also observe that the work function is strongly affected by adsorption. In particular, H adsorption results in an expansion of the interlayer distance between the topmost layers of the film. Furthermore, after atomic insertion, the interlayer distance of Pd/Pt(111) films is similar to the interlayer distance for bulk PdH0.6, which indicates that these thin films can act as precursor states for hydride formation.