Interpretation of H2-TPR from Cu-CHA Using First-Principles Calculations.

Temperature-programmed reduction and oxidation are used to obtain information on the presence and abundance of different species in complex catalytic materials. The interpretation of the temperature-programmed reaction profiles is, however, often challenging. One example is H2 temperature-programmed reduction (H2-TPR) of Cu-chabazite (Cu-CHA), which is a material used for ammonia assisted selective catalytic reduction of NOx (NH3-SCR). The TPR profiles of Cu-CHA consist generally of three main peaks. A peak at 220 °C is commonly assigned to ZCuOH, whereas peaks at 360 and 500 °C generally are assigned to Z2Cu, where Z represents an Al site. Here, we analyze H2-TPR over Cu-CHA by density functional theory calculations, microkinetic modeling, and TPR measurements of samples pretreated to have a dominant Cu species. We find that H2 can react with Cu ions in oxidation state +2, whereas adsorption on Cu ions in +1 is endothermic. Kinetic modeling of the TPR profiles suggests that the 220 °C peak can be assigned to Z2CuOCu and ZCuOH, whereas the peaks at higher temperatures can be assigned to paired Z2Cu and Z2CuHOOHCu species (360 °C) or paired Z2Cu and Z2CuOOCu (500 °C). The results are in good agreement with the experiments and facilitate the interpretation of future TPR experiments.

In Situ Metal Deposition on Perhydropolysilazane-Derived Silica for Structural Color Surfaces with Antiviral Activity.

Structural coloration has recently sparked considerable attention on the laboratory and industrial scale. Structural colors can create vivid, saturated, and long-lasting colors on metallic surfaces for optical filters, digital displays, and surface decoration. This study used an all-solution, low-cost method, free of a specific setup procedure, to fabricate structural colors of a multilayered metal-dielectric structure based on interference effects within a Fabry-Perot cavity. The insulating (dielectric) layer was produced from perhydropolysilazane, an inorganic silicon-containing polymer, from which hydrogen was liberated during conversion into silica and applied in situ to reduce metallic nanoparticles on the silica surface. This simple manufacturing technique contributes to the fabrication of large, high-quality surfaces, which could potentially be employed for surface decoration. The fabricated surfaces also exhibited excellent hydrophobic properties with contact angles up to 137°, endowing them with self-cleaning properties. In addition, the antiviral and antibacterial impact of the silver (Ag)/silica (SiO2)/stainless steel (SUS) film was also examined, as Ag has been reported to have antimicrobial and, recently, antiviral properties. According to three independently conducted antiviral assays, the fluorescence expression of virus-infected cells, PCR analysis, and modified tissue culture infectious dose assay, the film inhibited lentivirus by 75, 97, and 99% when exposed to the virus for 20 min, 1 h, and 20 min, respectively. Furthermore, the film had exceptional antibacterial activity with no colony growth observed for 24 and 12 h of inoculation. It is thus conceivable that these structural color-based films can be used to not only decorate metal surfaces with aesthetic colors but also limit virus and bacterium propagation successfully.

Lanthanide and Ladder-Structured Polysilsesquioxane Composites for Transparent Color Conversion Layers.

Ladder-type polysilsesquioxanes (LPSQs) containing phenyl as a high refractive index unit and cyclic epoxy as a curable unit were found to be excellent candidates for a transparent color conversion layer for displays due to being miscible with organic solvents and amenable to transparent film formation. Therefore, the LPSQs were combined with luminescent lanthanide metals, europium Eu(III), and terbium Tb(III), to fabricate transparent films with various emission colors, including red, orange, yellow, and green. The high luminescence and transmittance properties of the LPSQs-lanthanide composite films after thermal curing were attributed to chelating properties of hydroxyl and polyether side chains of LPSQs to lanthanide ions, as well as a light sensitizing effect of phenyl side chains of the LPSQs. Furthermore, Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy and nanoindentation tests indicated that the addition of the nanoparticles to the LPSQs moderately enhanced the epoxy conversion rate and substantially improved the wear resistance, including hardness, adhesion, and insusceptibility to atmospheric corrosion in a saline environment. Thus, the achieved LPGSG-lanthanide hybrid organic-inorganic material could effectively serve as a color conversion layer for displays.