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Filtration properties of membranes obtained by deposition of a few layer graphene oxide onto a polyamide support, with and without borate treatment, were examined. Filtrations of water, dilute solutions of electrolytes (Na2 SO4, NaCl, MgSO4, MgCl2 ), and dyes (bromophenol blue, eriochrome black T) were performed. It was found that the observed electrolyte retention series (Na2 SO4 > NaCl > MgSO4 > MgCl2 ) was in accordance with the Donnan exclusion theory. The membrane treated with borate and of higher graphene oxide load showed higher retention of sulfates than the untreated one. Despite of lower molecular weight, eriochrome black T was practically completely rejected by both types of membranes, contrary to bromophenol blue, irrespectively of its form (undissociated – retention 68%, dissociated – 85%). [ABSTRACT FROM AUTHOR]

Novel Ln-MOF with microrods shape were successfully combined with ZnIn 2 S 4 (ZIS) microsphere and used for photocatalytic hydrogen generation under UV–Vis and visible light. The Ln-MOFs/ZIS system comprises lanthanide-carboxylate coordination networks (Tm and Gd as metal ions, and 1,3,5-benzenetricarboxylic acid (BTC) as the organic linker) deposited on ZnIn 2 S 4 microspheres. Effect of the amount of ((Tm,Gd)-BTC) (1, 5, 10 wt%) on the optical properties and photocatalytic hydrogen evolution performance was investigated. ZIS microsphere shows the marigold flower-like morphology and hexagonal polytopic crystal form. Our results proved that the combination of ZIS microsphere, Ln-MOF and Pt nanoparticles (NPs) caused significant enhancement in hydrogen generation. Amount of formed hydrogen was raised from 196.3 to 7782.1 μmol g−1 for pristine ZIS and ZIS decorated with 1% (Tm, Gd)-BTC/Pt under UV–Vis light, respectively. [Display omitted] • Novel composite of (Tm,Gd)-BTC with ZnIn 2 S 4 microsphere. • Highly efficient photocatalytic performance compared to ZnIn 2 S 4. • Amount of H 2 formed over ZIS/1%Ln-MOF/Pt was 11,866,57 μmol g−1 under UV–Vis. • 40 times greater photocatalytic H 2 evolution for ZIS/1%Ln-MOF/Pt than for ZIS/Pt. [ABSTRACT FROM AUTHOR]

The generation of stable, high-performance photocatalysts with appropriate charge distribution for solar energy conversion is currently one of the urgent missions of photocatalytic science. Recent studies have shown that the Janus NPs with characteristic varied, asymmetric structure may boost overall efficiency of photocatalys. However, there is still a lack of systematic studies in which Janus-type particles are used in the hydrogen generation reaction in the visible light range. Herein, a different structures from Janus NPs, Janus-like to multi-headed structure based on ZnS and Ag were designed representatively through systematical characterization and theoretical calculation that have been targeted at efficient visible-light-driven H 2 generation. It has been shown that typical asymetric structures of Janus NPs characterised more active in the photocatalytic reaction of hydrogen generation in visible light than Janus-like and multi-headed structures and pure ZnS nanoparticles. The H 2 yield is related to the structure of Janus-type particles and thus to the formation of Ag and Zn oxides surface species for different structures. Systematic knowledge provided by a combined experimental and computational study may help enhance the efficiency of controlling Janus-type particles through appropriate structural manipulation at the early stage of the design process (before synthesis). [Display omitted] • The H 2 yield (λ > 420 nm) is related to the structure of Janus-type particles. • PCA analysis prove the value of the specific structural features on H 2 efficiency. • Action spectra of the best photocatalytic sample was investigated. • Charge-transfer processes of photocatalytic hydrogen evolution has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: The porous structure of the raw and the modified clinoptilolite has been investigated by nitrogen adsorption method, polarized light, scanning electron and atomic force microscopy as well as by thermogravimetric analysis. The relative moisture, specific gravity, bulk density and inter-particle porosity have been tested using thermostatic, pycnometric and hydrostatic weighing methods. The geometric method has been used to calculate the external surface area of the clinoptilolite crystallites in the clinoptilolite rock and to evaluate the volume of the clinoptilolite framework channels. Generally two types of porosities such as primary porosity and secondary one are observed. The primary porosity may be defined as microporosity presented by nanotube system of the clinoptilolite 3-dimensional aluminosilicate framework. The secondary porosity is formed by meso- and macropores, where the first ones are presented by slot pores determined mainly by cleavability of the zeolite crystallites. Total volume of the zeolite channels equals 0.332cm3/g which has been obtained using a geometric method. Micropores volumes of the raw and the acid-treated samples are 0.0031 and 0.0342cm3/g by nitrogen adsorption, respectively. According to thermogravimetric analysis the structural water lost at 150–750°C placed the pore volume 0.087cm3/g with the surface area 360m2/g. [ABSTRACT FROM AUTHOR]

• Electrochemical study of conducting polymer/carbon nanostructures composite is presented. • Influence of electrolyte type on capacitance values and cycling stability of composites is shown. • Diffusion controlled and non-diffusion controlled capacitance contributions are calculated. • Trasatti's analysis and Conway's equation are used to distinguish kinetics of electrode processes. • Scan rate range taken for linear fitting and extrapolation of parameters in both methods is discussed. In this work electrochemical performance of thin composite films consisted of poly(3,4-ethylenedioxythiophene) (PEDOT), graphene oxide (GOx) and oxidized multiwalled carbon nanotubes (oxMWCNTs) is investigated in various sulphates (Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 , MgSO 4) and acidic (H 2 SO 4) electrolytes. Capacitance values, rate capability and cycling stability achieved for the composite layers are correlated with the electrolytes' properties such as the conductivity, viscosity, cation size and pH. The highest capacitance values are achieved in acidic solution (98.6 mF cm−2 at 1 mA cm−2), whereas cycling stability is better in neutral electrolytes (88.4% of initial capacitance value after 10′000 cycles recorded for symmetric supercapacitor in 0.5 M MgSO 4 solution). Diffusion controlled and non-diffusion controlled capacitance contributions are calculated and the results are discussed considering various ranges of sweep rates taken into account in the linear fitting and extrapolation of parameters. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting has great potential in solar-hydrogen production as a low-cost and environmentally friendly method. Different unique techniques used to obtain photocatalysts with various modifications to improve H 2 generation have been introduced. In the present work, SrTiO 3 was successfully synthesized via the solvothermal method in the presence of ionic liquid (IL) - 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) followed by surface decoration with Pt particles using the photodeposition method. The effect of the noble metal content and presence of IL on the morphology, optical and surface properties of SrTiO 3 , thereby the effectiveness of hydrogen generation, has been thoroughly examined and presented. Unexpectedly, the presence of [BMIM][Br] at the SrTiO 3 surface affected the interaction between the semiconductor surface and platinum particles formed throughout photodeposition. Platinum particles at the surface of SrTiO 3 _IL were found to be in the form of 2D clusters with a size of 1 nm. In comparison, Pt deposited on SrTiO 3 photocatalyst without application of IL created larger, three-dimensional structures with a diameter exceeding 5 nm. This is the reason why the total amount of platinum deposited on the SrTiO 3 _IL sample is smaller than that on SrTiO 3 and justifies a higher efficiency of hydrogen generation of Pt modified SrTiO 3 photocatalyst in comparison to SrTiO 3 prepared in the presence of IL. The mechanism of H 2 generation in the water-splitting reaction in the presence of SrTiO 3 _Pt photocatalyst was discussed. • Pt decorated SrTiO 3 was obtained in the presence of ILs for photocatalytic H 2 evolution. • The photocatalytic hydrogen evolution rate of SrTiO 3 _IL_Pt is 677.84 μmol/min. • Samples prepared with ILs is covered with Pt clusters with diameter ~1 nm. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Accidental freezing of aluminum-based vaccines occurs during their storage and transportation, in both developed and developing countries. Freezing damages the freeze-sensitive aluminum adjuvanted vaccines, through separation of lattice between aluminum adjuvant and antigen, leading to formation of aluminum aggregates, and loss of potency. In this study, we examined Alhydrogel™ ([AlO(OH)]x n H 2 O, aluminum hydroxide, hydrated for adsorption) stored under recommended conditions, and exposed to freezing temperature until solid-frozen. The main purpose of our research was to determine the destruction areas of the solid-frozen Alhydrogel™ using selected methods of scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy and transmission electron microscopy working in diffraction mode. The Zeta potential evaluation, measurements of albumin adsorption power, thermogravimetric analysis and estimation of the mass loss after drying indicated significant structural (physical) and chemical differences between the freeze-damaged and non-frozen vaccine adjuvant. The presented results are important to better understand the type and nature of damages occurring in freeze-damaged aluminum-based vaccines. These results can be used in future studies to improve the temperature stability of aluminum adjuvanted vaccines. [ABSTRACT FROM AUTHOR]

In this paper, several approaches to the synthesis of molybdenum-based electrode materials for supercapacitors are presented, including anodization, hydrothermal process and annealing. For the material prepared via anodization of a molybdenum plate, followed by a hydrothermal process in thiourea aqueous solution, a thorough study of the Pt-surface modification through repetitive cycling in 1 M sulfuric acid with Pt acting as a counter electrode is performed, including X-ray photoelectron spectroscopy analysis and energy storage mechanism contribution. Along with the increasing number of cycles, an increase of the capacitance value is observed up to 1.064 F cm−2 after 60 000 cycles, resulting in more than tenfold growth (by over 1 150%). The analysis reveals progressive changes in the electrode material's chemical composition and the increasing pseudocapacitance contribution in energy storage processes, which is strictly caused by the formation of mixed molybdenum oxides with oxygen vacancies. Thus, Pt-surface modification effectively improves the electrochemical performance of the electrode material with excellent coulombic efficiency and capacitance retention. In a symmetric two-electrode configuration with Pt-modified electrode materials, the areal capacitance of 140.5 mF cm−2 is obtained after 50 000 cycles (with capacitance retention of 123%) indicating that Pt-surface modification of MoS 2 may provide a novel approach for electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

A facile and effective plasma sputtering method for the preparation of a visible light active photocatalyst - rhombic dodecahedral silver phosphate Ag 3 PO 4 covered with nanographene (Ag 3 PO 4 -GR) with improved stability has been developed. Proposed method allows for the usage of readily available materials for nanographene sputtering and for easy scaling-up. The stability improvement, confirmed by visible light-induced phenol degradation experiment, could be attributed to the synergistic effect of the silver phosphate particles and graphene material allowing for migration of metallic silver nanoparticles from semiconductor's surface to graphene body keeping the semiconductors surface "silver free". Also due to its conductive properties, nanographene may additionally be preventing electron-hole recombination and metallic silver formation. [Display omitted] [ABSTRACT FROM AUTHOR]

The influence of hydrothermal annealing (HA) of TiO 2 nanotubes (TiO 2 -NTs) in various baths (H 2 O, LiNO 3 , NaNO 3 , KNO 3 performed for 4 h, 24 h, 64 h), on their photocatalytic and photoelectrocatalytic properties, was studied. The use of electrolytes was to enable the monitoring of photoactivity changes as a result of the expected impact on the population of hydroxyl groups on the surface. The assumption turned out to be correct and it was proved that the presence of Li+, Na+ or K+ does not allow achieving the same increases in photoactivity as observed for water. Modified samples exhibit significantly decreased F, P and carbon containing species. The length of the HA annealing time considerably affected the geometry of the nanotubes: eliminated clusters, changing the tilting angle of nanotubes, the wall thickness and inter-nanotube distance. Morphology changes due to HA treatment were associated with the interference phenomenon recorded as maximum in the Vis range. HA treatment in water brings about the most photoactive and photoelectroactive material characterized with minor modification in the optical bandgap and position of the flat bad potential. The optical energy bandgap values for electrodes containing alkali metals were reduced (up to 2.72 eV) and flat-band potential was shifted towards the anodic direction (up to 0.25 V disparity). However, increased activity as photocatalysts in the methylene blue degradation process and higher photocurrent generation was achieved for samples after modification in distilled water than in electrolytes, but these parameters are still better in comparison to unmodified titania nanotubes. Long-term treatment in water and electrolytes reduced threshold potentials for oxygen evolution reaction. The studies confirmed the effectiveness of the hydrothermal method for obtaining better photocatalytic parameters of TiO 2 -NTs and indicate that the presence of alkali metals is not favourable for maintaining high photocatalytic parameters. [ABSTRACT FROM AUTHOR]

In this work, we study the impact of the preceramic precursor vinyltriethoxysilane (VTES) on the electrochemical performance of silicon oxycarbide (SiOC) glass/graphite composites. We apply an innovative approach based on high-power ultrasounds in order to obtain highly homogenous composites with a uniform distribution of small graphitic flakes. This procedure enhances gelation and drying of VTES-based preceramic polymer/graphite blends. The SiOC/graphite composites reveal stable capacities (up to 520 mAh g−1 after 270 cycles), which are much higher than the sum derived from the ratio of the components. Additionally, the first cycle Coulombic efficiencies obtained for the composites are 15% higher than that of the pristine VTES-based SiOC ceramic. These properties are identified as the synergistic effect, originated from the addition of graphite to VTES-based SiOCs. Interestingly, such improvement in electrochemical performance is not noticed in the case of analogous SiOC/graphite composites based on phenyltriethoxysilane (PhTES) precursor. The microstructural investigation of the composites based on two different preceramic precursors using solid-state 29Si NMR and Raman Spectroscopy unveils the reason for such discrepancy in their electrochemical behaviour. [Display omitted] • SiOC/C composites are prepared by a novel high-power ultrasounds-assisted synthesis • Graphitic flakes are uniformly distributed and partially exfoliated within the ceramic • Microstructural dissimilarities of SiOC/C based on various precursors are discussed • Synergistic effect on electrochemical properties of SiOC/C depends on microstructure • SiOC/C electrodes exhibit improved first cycle Coulombic efficiency and high capacity [ABSTRACT FROM AUTHOR]