Single crystal gold clusters (10 nm in size) have been collectively manipulated on mono- and bi-layered MoS2 islands (up to 20 µm) grown on SiO2 using AFM. On the monolayer the clusters tend to move in a direction corresponding to the zigzag alignment of the Mo and S atoms, and assemble into long striation patterns parallel to the scan direction. The distance between consecutive stripes is inversely proportional to the cluster concentration and size. A more detailed observation based on SEM shows that within each stripe the clusters remain separated by gaps of few nm in width possibly caused by electrostatic repulsion and/or the roughness of the SiO2 substrate (~2 nm). The stripes also proved to be thermally stable, preserving their superstructures up to 823 K. On the bilayer gold clusters are much less prone to move and assemble into stripes. These results suggest that the formation of nanostructures resulting from collective manipulation of metal clusters can be oriented by a properly chosen scan path in a rather straightforward way (as compared to one-by-one displacement of single clusters). The goal of forming µm-long but nm-thin wires with a geometrically defined shape could be easily reached with the use of smoother substrates or TMD materials with lesser charge transfer to metals adsorbed on them.

Titanium is the metal of choice for many implantable devices including dental prostheses, orthopaedic devices and cardiac pacemakers. Titanium and its alloys are favoured for hard tissue replacement because of their high strength to density ratio providing excellent mechanical properties and biocompatible surface characteristics promoting in-vivo passivation due to spontaneous formation of a native protective oxide layer in the presence of an oxidizer. This study focuses on the development of a three-dimensional chemical, mechanical, surface nano-structuring (CMNS) process to induce smoothness or controlled nano-roughness on the bio-implant surfaces, particularly for applications in dental implants. CMNS is an extension of the chemical mechanical polishing (CMP) process. CMP is utilized in microelectronics manufacturing for planarizing the wafer surfaces to enable photolithography and multilayer metallization. In biomaterials applications, the same approach can be utilized to induce controlled surface nanostructure on three-dimensional implantable objects to promote or demote cell attachment. As a synergistic method of nano-structuring on the implant surfaces, CMNS also makes the titanium surface more adaptable for the bio-compatible coatings as well as the cell and tissue growth as demonstrated by the electrochemical and surface wettability evaluations on implants prepared by DI-water machining versus oil based machining.

The most promising candidate as an everyday alternative to lithium-ion batteries (LIBs) are sodium-ion batteries (NIBs). This is not only due to Na abundance, but also because the main principles and cell structure are very similar to LIBs. Due to these benefits, NIBs are expected to be used in applications related to large-scale energy storage systems and other applications not requiring top-performance in terms of volumetric capacity. One important issue that has hindered the large scale application of NIBs is the anode material. Graphite and silicon, which have been widely applied as anodes in NIBs, do not show great performance. Hard carbons look very promising in terms of their abundance and low cost, but they tend to suffer from instability, in particular over the long term. In this work we explore a carbon-coated TiO2 nanoparticle system that looks very promising in terms of stability, abundance, low-cost, and most importantly that safety of the cell, since it does not suffer from potential sodium plating during cycling. Maintaining a nano-size and consistent morphology of the active material is a crucial parameter for maintaining a well-functioning cell upon cycling. In this work we applied Anomalous Small Angle X-Ray Scattering (ASAXS) for the first time at the Ti K-edge of TiO2 anatase nanoparticles on different cycled composite electrodes in order to have a complete morphological overview of the modifications induced by sodiation and desodiation. This work also demonstrates for the first time that the nanosize of the TiO2 is maintained upon cycling, which is in agreement with the electrochemical stability.

Quantum Dots (QDs) like Cadmium Sulphide have exciting applications, consequent to their size-dependent optical properties. This compound is used as a pigment in papers, paint, and it can also be found in solar cells. Due to the high use of nanoparticles in society, there is a significant concern in the scientific community about the potential toxicity of these nanomaterials in aquatic environments. According to this main problem, we have a theoretical assumption that Cadmium Sulphide (CdS) particles at nanoscale are more toxic than those in macroscale (bulk), and a higher concentration means higher toxicity. To verify its toxicity in the aquatic environment, first, we need to make sure the nanoparticles are soluble in water. Based in the mentioned before, the objectives of this research were: (i) synthesize Cadmium Sulphide QDs in aqueous phase in presence of biocompatible molecules like L-Glutathione and N-Acetyl-L-cysteine, (ii) characterize the quantum dots optically, structurally and morphologically and; (iii) evaluate the toxicity of Cadmium Sulphide in biological systems. CdS, L-Glutathione-covered CdS and N-Acetyl-L-Cysteine-covered CdS evidenced shoulder peaks at 473 nm (2.40 eV), 450 nm (2.62 eV) and, 381 (3.03 eV) nm, respectively. A broad and high emission peak centered at 545 nm was observed for CdS Nps covered with N-acetyl-L cysteine; whereas as QDs without cover and those covered with L-glutathione showed weak peaks in the visible range (470 nm-650 nm). The presence of L-Glutathione or N-Acetyl-L-cysteine on the quantum dots surface was verified by Infrared Spectroscopy. Energy Dispersive X-Ray Spectroscopy (EDX) assays evidenced the chemical composition of produced nanostructures having 57.91% of S and 42.09% of Cd. The morphology and the size were carried out by High-Resolution Transmission Electron Microscopy (HR-TEM). In this way, nanoparticles were spherical and with a size of ~3 nm. Toxicity results evidence that nanoparticles covered with N-Acetyl-L-Cysteine had a negative interaction in marine organisms at concentrations higher than 700 ppm, after 24 or 48 hours of contact. Also, CdS bulk showed absence of toxicity to marine crustaceans.

The quality of the shell coating around nanorods is critical in device applications. Conventional physical vapor deposition (PVD) techniques can be utilized for highly conformal shell coating formation in core-shell structure devices. To identify scalable fabrication techniques for conformal shell coatings, Monte Carlo (MC) simulations of PVD growth were performed under different atomic flux distributions and angles on arrays of glancing angle deposition (GLAD) nanorods, which were also generated by MC simulations. We investigated the conformality of PVD films (shell) around GLAD rod arrays (core) and analyzed the thickness uniformity of the shell layer across the sidewalls of rods. Our results show that Angular Flux-Normal Angle (A-NAD), which might correspond to high-pressure sputter deposition at normal incidence (HIPS at θ = 0o) can generate better conformal shell coating compared to others. In Uniform Flux-Normal Angle technique (U-NAD), which corresponds to a thermal evaporation deposition, the growth suffers from poor sidewall coverage. In addition, introducing a small angle to the flux also improves the shell conformality. Therefore, high-pressure sputter deposition technique is expected to provide superior conformality for a catalyst or semiconductor coating around base nanorods, for example for fuel cell and solar cell applications, with the help of obliquely incident atoms of the HIPS flux.