Planar Silicene: A New Silicon Allotrope Epitaxially Grown by Segregation

2D sheets of graphene‐like silicon, namely planar silicene, are synthesized. This new silicon allotrope is prepared on Au(111) thin films grown on a Si(111) substrate in the process of surface segregation. Owing to its almost perfectly flat geometry it shares the atomic structure with graphene rather than with low‐buckled silicene. Scanning tunneling microscopy measurements clearly display an atomically resolved planar silicene honeycomb lattice. Ab initio density functional theory calculations fully support the experimental findings and predict a pure sp² atomic configuration of Si atoms. The present work is the first experimental evidence of epitaxial planar silicene.     

Kinetic modelling of the electrochemical mineralization of organic pollutants for wastewater treatment

The electrochemical mineralization of organic pollutants is a new technology for treatment of dilute wastewater (COD < 5 g L⁻¹). In this method, use of the electrical energy can produce complete oxidation of pollutants on high oxidation power anodes. An ideal anode for this type of treatment is a boron-doped diamond electrode (BDD) characterized by a high reactivity towards oxidation of organics. In the present work kinetic aspects of organic mineralization is discussed. The proposed theoretical kinetic model on boron-doped diamond anodes is in excellent agreement with experimental results. In addition economic aspects of electrochemical organic mineralization are reported.     

All solid-state electrochromic devices with gelatin-based electrolyte

6×8 cm² electrochromic devices (ECDs) with the configuration K-glass/EC-layer/electrolyte/ion-storage (IS) layer/K-glass, have been assembled using Nb₂O₅:Mo EC layers, a (CeO₂)_0.81–TiO₂ IS-layer and a new gelatin electrolyte containing Li⁺ ions. The structure of the electrolyte is X-ray amorphous. Its ionic conductivity passed by a maximum of 1.5×10⁻⁵ S/cm for a lithium concentration of 0.3 g/15 ml. The value increases with temperature and follows an Arrhenius law with an activation energy of 49.5 kJ/mol. All solid-state devices show a reversible gray coloration, a long-term stability of more than 25,000 switching cycles (±2.0 V/90 s), a transmission change at 550 nm between 60% (bleached state) and 40% (colored state) corresponding to a change of the optical density (ΔOD=0.15) with a coloration efficiency increasing from 10 cm²/C (initial cycle) to 23 cm²/C (25,000th cycle).     

Studies on the influence of tris(pentafluorophenyl)borane on the properties of ethylene carbonate, dimethyl carbonate and poly(ethylene oxide) dimethyl ether lithium trifluoromethanesulfonate electrolytes

In this paper we present our studies on the properties of battery electrolyte based on EC/DMC (ethylene carbonate/dimethyl carbonate, w/w ratio 2:5) and PEODME (poly(ethylene oxide) dimethyl ether) (M_w = 500) doped with LiCF₃SO₃-lithium trifluoromethanesulfonate (LiTf) and modified with TPFPB (tris(pentafluorophenyl)borane) as a potential anion trapping agent. We were particularly interested how this compound behaves in different solvents, e.g. battery mixture EC/DMC and model polymeric matrix PEODME. We also verified stability of the proposed solutions by means of DSC and FTIR, determined influence on conductivity and lithium transference numbers by impedance spectroscopy, and finally attempted to define mechanism of influence of boron addition on different systems.     

The kinetics and mechanism of the electroreduction of Bi(III) ions from chlorates (VII) with varied water activity

The influence of water activity on the mechanism and kinetics of Bi(III) ions electroreduction at dropping mercury electrode in chlorates (VII) using voltammetric and impedance methods was examined. The kinetic parameters determined in the examined solutions were correlated with water activity. The values of transfer coefficients, standard rate constants and activation energy point at the slight influence of supporting electrolyte concentration on the kinetics of Bi(III) electroreduction in 1-3 mol dm⁻³ chlorates (VII). In the concentration range of 4-8 mol dm⁻³ the values of transfer coefficients and standard rate constants increase considerably, whereas the values of activation energy decrease what testifies to the increase of reversibility of Bi(III) ions electroreduction. The character of the rate constants changes in the function of potential points at multi-stage process of Bi(III) ions electroreduction as well as a different mechanism of Bi(III) electroreduction in the solutions with low water activity in comparison with the solutions with high water activity.     

Adsorption of basic dyes from model aqueous solutions onto novel spherical silica support

Removal of CI Basic Blue 9 or CI Basic Red 5 from model aqueous solutions has been studied with spherical silica precipitated in an emulsion system used as an adsorbent. The process of removal of the dye impurities has been studied for the dyes in a wide range of concentrations (50–2000 mg dm⁻³) in model systems. The degree of dye adsorption, chemical stability of the pigments obtained and their detailed physicochemical and morphological characterisation have been ascertained. In particular, the dye removal method proposed has been found to be highly effective in removing CI Basic Blue 9 (99.9%). The degree of dye extraction from the silica (SiO₂) surface at the dye concentration in the model solutions in the range 1000–2000 mg dm⁻³ did not exceed 1.0%. The pigment composites produced are characterised by high uniformity of the particles (polydispersity index = 0.005) with the diameters ranging from 360 to 510 nm. The pigment particles are spherical in shape and of intense blue or red colour.     

High pressure and high temperature induced polymeric C60 nanocrystal

In this paper, C₆₀ nanosheets with polymeric phases have been obtained under various high pressures and high temperatures, including orthorhombic and tetragonal polymeric phases. The structures have been identified and compared with those of nanorods by photoluminescence and Raman spectroscopies. The main fluorescence band shifted from 1.70 eV in the monomeric phase to near infrared in the polymeric phase when pressure and temperature were increased. The difference of photoluminescence and Raman spectra between nanosheets and nanorods samples treated under the same conditions is probably caused by different polymerization degree in these samples because of different shapes.     

Photogeneration and photovoltaic effect in poly(N-vinylcarbazole):TiO2 bulk-heterojunction elaborated by hydrolysis–condensation reactions of TiO2 precursors

TiO₂:poly(N-vinylcarbazole) (PVK) bulk-heterojunctions (BHJ) have been elaborated from a blend of a TiO₂ precursor with the polymer in solution. The TiO₂ precursor is hydrolyzed with the surrounding air humidity in thin film. Titanium isopropoxide [Ti(ⁱOPr)₄] and Tetrakis (9H-carbazole-9-yl-ethyl-oxy) titanium [Ti(OeCarb)₄] were used as TiO₂ precursor. Photogeneration quantum yield in BHJ of TiO₂:PVK were determined by the surface potential decay (SPD) technique. Photovoltaic effect was studied in ITO/PEDOT:PSS/TiO₂:PVK/Al structures. It was found that the photovoltaic performance is strongly dependent on the homogeneity of the blends. The improved dispersion of the TiO₂ phase obtained with the precursor bearing a carbazole group allows efficient electron transport and fill factor enhancement of the photovoltaic devices.     

Flavonoid and Phenolic Acids Content and In Vitro Study of the Potential Anti-Aging Properties of Eutrema japonicum (Miq.) Koidz Cultivated in Wasabi Farm Poland

Skin aging is a natural, unavoidable, and complex process caused by oxidative stress. As a consequence, it leads to an increase in the activation of extracellular matrix disruption enzymes and DNA damage. The search for natural sources that inhibit these mechanisms can be a good approach to prevent skin aging. The purpose of our study was to evaluate the composition of flavonoids and phenolic acids in the extracts obtained from the flowers, roots, and leaves of Eutrema japonicum cultivated in Poland. Then, the resultant extracts were subjected to an assessment of antioxidant, anti-collagenase, anti-elastase, anti-hyaluronidase, antibacterial, and cytotoxic properties. It was demonstrated that the extract from the flowers had the highest content of flavonoid glycosides (17.15 mg/g DE). This extract showed the greatest antioxidant, anti-collagenase, anti-elastase, and anti-hyaluronidase activities compared to the other samples. Importantly, the collagenase inhibitory activity of this extract (93.34% ± 0.77%) was better than that of positive control epigallocatechin gallate (88.49% ± 0.45%). An undeniable advantage of this extract was also to possess moderate antibacterial properties and no cytotoxicity towards normal human skin fibroblasts. Our results suggest that extracts from E. japonicum flowers may be considered as a promising antiaging compound for applications in cosmetic formulations.