Ni-based oxides are widely investigated as catalysts for CO₂ methanation due to their high activity, high selectivity and low cost. The catalytic performances of Ni-based catalysts depend on support properties that strongly influence the dispersion of the catalytic active phase and the Ni–support interaction. Although the CO₂ methanation is widely studied, the structure sensitivity of methanation on nickel is not completely assessed. Ni/CeO₂ nanorods with different nickel/ceria molar ratios (0.05, 0.10, 0.20, 0.30) were prepared by one-pot hydrothermal synthesis. The effect of nickel content and metal particle size on catalytic activity and selectivity for CO₂ methanation were studied using CO₂:H₂ = 1:4 stoichiometric ratio at high space velocity (300 L g⁻¹ h⁻¹). Sample structure and morphology were studied by X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) analysis, field-emission scanning electron microscopy/energy-dispersive spectroscopy (FE-SEM/EDS), H₂-temperature programmed reduction (TPR), H₂-temperature-programmed desorption (TPD). Both the CO production and the turnover frequency appear depending on nickel particle size, suggesting a structure sensitivity of the CO₂ methanation on nickel supported on ceria.

Calcium oxalates are insoluble colorless or whitish salts constituting noble patina, on both natural and artificial stone artworks' surfaces, the presence of which is extremely valued. The oxalates are not considered detrimental to the substrate, however, being often accompanied by other substances such as gypsum, silicates, and pigmented particles. They may form very adherent, relatively thick and colored layers creating disfiguring effects and hindering legibility of the pictorial surface. For this reason it may be appropriate to diminish their thickness, but patina's partial preservation is particularly required calling for extremely gradual and controllable cleaning approach. Thinning of calcium oxalate patina from a detached 16th century fresco (from Sansepolcro) was performed through the use of laser (Nd:YAG and Er:YAG) systems and chemical means (Carbogel loaded 5 wt.% of tetrasodium EDTA). Optical coherence tomography (OCT), providing a non-invasive stratigraphic cross-section of the examined surface, allowed to distinguish the oxalate from the underlying original layers and therefore to have an overview about its distribution, to numerically evaluate patina's thickness range and to provide the information on the amount of the material both removed and left on the artwork's surface. Laser scanning conoscopic microprofilometry allowed for a high-density sampling of the artwork's surface providing a three-dimensional model of the surface pattern. The obtained 3D models were used to estimate the amount of material removed and to compare them with those provided by OCT. The successful exploitation of the proposed exceptional cleaning monitoring methodology may be seen as an innovative and valid support for the restorers in the conservation of mural painting or other surfaces covered by oxalate layers and may pilot more targeted, cautious and respectful cleaning intervention.

We report on tests to remove naturally and artificially aged shellac varnish by laser and traditional chemical cleaning from the substrates of mural paintings. Optical tools were used for the evaluation of cleaning processes, in particular laser microprofilometry to assess the changes in the surface morphology and time-domain confocal optical coherence tomography (OCT) to evaluate varnish thickness. The cleaning assessment was integrated with molecular characterization provided by portable Fourier transform infrared spectroscopy operating in reflectance mode, and colorimetric measurements. This complete analytical approach led to optimized laser-based cleaning tests at 1.9 and 2.6 J/cm2 in the presence of isopropanol, which ensured controllable and safe partial removal of shellac varnish without alteration to the substrate morphology.

The nanorod morphology of the CeO₂ support has been recognized as more beneficial than other morphologies for catalytic activity in the dry reforming of methane. Ni/nanorod-CeO₂ catalysts with different Ni contents were prepared by one-pot hydrothermal synthesis. Samples were characterized by X-ray diffraction (XRD), H₂-temperature-programmed reduction (H₂-TPR), H₂-temperature-programmed desorption (H₂-TPD), field emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS), Brunauer–Emmet–Teller (BET) and Barrett–Joyner–Halenda (BHJ) analysis. The effect of Ni content on the size and the intrinsic strain of ceria was analyzed by the Size–Strain plot and Williamson–Hall plot of XRD data. The average Ni particle size and Ni dispersion were determined by H₂-TPD. XRD and H₂-TPR analysis revealed a strong Ni–support interaction that limited nickel sintering. The activity for the dry reforming of methane was tested with the stoichiometric mixture CO₂:CH₄:N₂:He = 20:20:20:140, gas hourly space velocity (GHSV) = 300 L g⁻¹ h⁻¹, and temperatures in the range of 545–800 °C. The turnover frequency (TOF) value increased linearly with the average Ni particle size in the range of 5.5–33 nm, suggesting the structure sensitivity of the reaction. Samples with Ni loading of 4–12 wt.% showed high H₂/CO selectivity and stability over time on stream, whereas the sample with a Ni loading of 2 wt.% was less selective and underwent rapid deactivation. Only a small amount of nanotubular carbon was observed by FE-SEM after the time-on-stream experiment. Deactivation of the low-Ni-content sample is ascribed to the easier oxidation of the small Ni particles.

Mesoporous silica nanoparticles (MSNPs) are currently used in different fields like catalysis, nanomedicine, and conservation science, taking advantage of their high surface area. Here, we synthesized and functionalized mesoporous dendritic fibrous nanoparticles to realize a smart delivery system of protective agents for metals. Different MSNPs were obtained via the microemulsion method followed by a hydrothermal or refluxing treatment at different w/o ratios, times, and temperatures. Dendritic spherical silica nanoparticles with specific features such as an appropriate size (450 nm), a very large surface area (600 m² g⁻¹), and a high yield synthesis (86%) were selected for surface modification. The fiber surface of the selected MSNPs was functionalized with 3-aminopropyl triethoxysilane (3-APTES). 3-APTES works as a pH-driven “nanogate”, suppressing the immediate leakage of the total guest molecule load and modulating the release as a function of pH conditions. Surface-modified MSNPs were tested as a reservoir of the most diffused corrosion inhibitors: Mercaptobenzothiazole (MBT) and 1H-Benzotriazole (BTA); their release properties were studied in solutions with pH = 4 and 7. Functionalized and non-functionalized MSNPs showed a good loading efficiency of guest molecules (34–64%) and a pH-dependent release of the corrosion inhibitors on a timescale of several hours.

Although some recent developments in nanotechnology made the prospects of a direct mechanical manipulation of micro- or nano-objects quite realistic, there are still several concerns and difficulties that affect such an endeavor. This is probably due to the large base of knowledge that is necessary to approach the problem of handling a nano-object by means of a nano- or micro-device. Therefore, any progress in this field is possible only by means of an integrated and interdisciplinary approach, which takes into account different aspects of the phenomenon. During the actual pioneering phase, there is a certain convenience in handling nano-objects that: (a) have peculiar known characteristics; (b) are easily recognizable, and (c) are interesting to the scientific community. This paper presents the interdisciplinary activities that were necessary to set up an experiment where specifically synthesized SiO₂ particles came in contact with the tips of specifically-designed and -fabricated nanomanipulators. SiO₂ mesoporous nanoparticles (KCC-1), having a peculiar dendritic structure, have been selected as a suitable nano-object because of the possibility to easily modulate their morphology. The expected contact force has been also calculated by means of Finite Element Analysis (FEA) electro-mechanical simulations.