Density functional theory is used for the evaluation of surface segregation, trends for dissolution of Pt surface atoms in acid medium, and oxygen reduction reaction activity of core-shell materials, containing a monolayer of platinum over a monometallic or bimetallic core. Two groups of cores are investigated: Pt/X with X = Ir, Au; Pd, Rh, Ag; Co, Ni, Cu; and Pt/Pd(3)X, with X = Co, Fe, Cr, V, Ti, Ir, Re. It is found that all the 4d and 5d pure cores may serve as stable cores, and their beneficial effect on the Pt monolayer may be further tuned by alloying the core to another element, here chosen from 3d or 5d groups. The Pd(3)X cores enhance the stability of the surface Pt atoms both in vacuum and under adsorbed oxygen; however the high oxygen philicity of some of the X elements induces their surface segregation that may cause surface poisoning with oxygenated species and their dissolution in acid medium.

This study presents the additive manufacture of objects using mass-functionalized photo-resins, which are additively photopolymerized using the laser stereolithography technique. The mass functionalization is based on the incorporation of copper nanowires used as fillers at different concentrations. Cylindrical and tensile test probes are designed and manufactured in a layer-by-layer approach using a low-cost laser stereolithography system working with a layer thickness of 100   µ m . The morphological, mechanical, thermal and chemical results help to show the viability and potential that this combination of mass-functionalized resins and technological processes may have in the near future, once key challenges are solved. Finally, some potential applications are also discussed.

Different zirconium precursors lead to different bulk properties but similar defective surfaces.

Amorphous silicon dioxide films arise naturally by exposure of silicon surfaces to atmospheric environments. When used as electrodes in Li-ion batteries, the characterization of surface lithiation is relevant to the understanding of the performance of Si anodes. In this work, density functional theory analyses of the lithiation of an amorphous silicon dioxide film reveal the lithiation mechanisms and the role of the surface functional groups on the lithiation reactions and on the structure of the lithiated film. The surface concentration of silanol groups and structure of the optimized model of amorphous hydroxylated silicon dioxide film agree with those observed experimentally. It is found that Li is incorporated via breaking of Si−O bonds and partial reduction of the Si atoms. Evaluation of the formation energy for lithiation of the film indicates that the film would saturate at a Li/Si ratio of 3.48. Analyses of radial distribution functions and coordination numbers show the evolution of the structure upon lithiation, indicating the presence of Li 6 O complexes stabilized by the surrounding Si atoms.

Density functional theory is used to evaluate the adsorption of carbon on stepped (211) cobalt surfaces. It is found that the 4-fold step hollow sites on (100) planes are the most stable adsorption sites for carbon, followed by the 3-fold hcp sites located in (111) terraces where adsorption per carbon atom is 0.7-0.9 eV less stable than that on the step sites. When the carbon concentration over the surface increases, adsorption of carbon chains is also favorable, and at even higher carbon pressures, interaction of adsorbed chains may lead to the formation of graphene sheets parallel to the (100) plane or to the formation of horizontally aligned seminanotubes. Formation of these carbon structures is accompanied by oxidation of the cobalt atoms, especially those forming the 4-fold step hollow site, whereas cobalt terrace sites become negatively charged. We discuss the significance of our results in relation to the catalyzed growth of single-walled carbon nanotubes on cobalt nanoparticles.