Developing a photocatalysis system to generate hydrogen from water is a topic of great interest for fundamental and practical importance. In this study, hydrogen production by a new Z-scheme photocatalysis water splitting system was examined over Rh modified K4Nb6O17 nanosheets and Pt/WO3 photocatalysts for H2 evolution and O2 evolution with I-/IO3 - electron mediator under UV light irradiation. The H2 evolution photocatalyst, Rh/K4Nb6O17 nanosheets with a slit like framework, was prepared by exfoliation of and proton exchange reaction. Pt/WO3 prepared by incipient-wetness impregnation method was used as O2 evolution photocatalyst. The catalysts were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy analysis (XPS), and ultraviolet-visible spectroscopy (UV-vis). These catalysts characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-Vis). In this study, we developed a facile method of preparing K4Nb6O17 nanosheets containing Rh nanoparticles. Our results show that I- concentration and pH of reaction solution have significant influences on the photocatalytic activity. The combination of Rh modified K4Nb6O17 nanosheets with Pt/WO3 achieves a very high photoactivity (H2: 4240 O2: 1622 (μmol g-1 h-1)).
In the presented work composite ferroelectric/ferrimagnetic ceramics have been obtained and described. The investigated material is based on PMN-PT powders and Ni-Zn ferrite powder. The Powders of ferroelectric component (i.e. (1–x)PMN-(x)PT with x from 0.25 to 0.40 with step 0.03 were synthesized using the sol-gel method. The magnetic component i.e. nickel-zinc ferrite was obtained from oxides using the classic method of obtaining ceramics. The compositions of PMN–PT used by us have rhombohedral or tetragonal symmetries, or belong to morphotropic region. The final ceramic composite samples were obtained using the classic method of ceramic technology with calcination route and final pressureless densification using free sintering. In this paper, XRD, EDS dielectric and magnetic properties have been investigated and described for the obtained composite ceramic samples.
In this contribution, the preparation and characterization of new shape-memory epoxy based nanocomposites filled with modified multiwalled carbon nanotubes are reported. The study has been focused on the optimization of the preparation methodology and on the evaluation of the effect of different contents of surface modified carbon nanotubes on the properties and the microstructure of the obtained materials. In particular, dispersion test, infrared spectroscopy, thermogravimetric analysis and bright field transmission electron microscopy have been carried out to analyze the modified filler. Moreover, the obtained nanocomposites have been characterized by morphological analysis, differential scanning calorimetry, thermomechanical analysis and X-ray analysis in order to clarify the effect of the nanofiller on the structure and shape memory properties of the materials.
The main aim of this study was to electrochemically synthesize and characterise bismuth vanadate (BiVO4) photoelectrodes for photoelectrochemical (PEC) water splitting. The influence of annealing temperature on the nanostructured semiconductor BiVO4 thin film structure was studied systematically. This was followed by advanced characterisation of the BiVO4 photoelectrodes by using field emission-scanning electron microscopy (FE-SEM), Raman spectroscopy, photoluminescence and PEC properties measurements. When the electrochemically synthesized BiVO4 thin films were subjected to different annealing temperatures, phase transitions occurred for tetragonal BiVO4 at 300 oC and monoclinic BiVO4 at 400 oC. Through this study, it was found that the annealing treatment at 400 oC resulted in the highest photocurrent density (i.e. photoactivity) of 1.23 mA/cm2 at 0.6 V vs. Ag/AgCl. Finally, the BiVO4/CuO heterojunction photoelectrode was also fabricated in order to further enhance its photoactivity under visible light irradiation.
In this paper ferroelectric–ferromagnetic composites based on a doped PZT-type and ferrite powders are presented. Ferroelectric powder (in amount of 85.0 wt-%) was based on multicomponent PZT-type materials: i) Pb(Zr0.51Ti0.49)O3+0.2%at.Bi2O3+ 0.03%at.Nb2O5+0.06%at.MnO2,ii) Pb0.84Ba0.16(Zr0.54Ti0.46)O3+1.0%at.Nb2O5, while nickel–zinc ferrite Ni0.64Zn0.36Fe2O4 (in amount of 15.0 wt-%) served as the magnetic component of the composite samples. The synthesis of the ferroelectric–ferromagnetic composite powders was performed by solid state, while final densification of the synthesized powders was achieved by free sintering. Conducted tests indicate obtained ferroelectromagnetic ceramic composites (PZT-ferrite type) to exhibit good properties giving the possibility for their use as magnetoelectric transducers.
The latest research directions related to the design of protective clothing concern implementation of smart materials, such as shape memory alloys (SMA), that allow for its functionalization which could not be achieved with traditional materials. As a result of the research project, a thermo-mechanical treatment program of a nickel-titanium alloy has been elaborated. This program allows to obtain active elements in a form of conical springs that are characterized by twoway shape memory effect and predestined for implementation into protective clothing. Textile materials with SMA elements intended for clothing protecting against flame, radiant heat and molten splashes have been developed and manufactured. Laboratory tests aimed at evaluation of the obtained shape change effect were performed according to the specially modified testing methodology. The test results indicated that SMA elements caused an improvement of the protective properties of textile materials due to their increased thickness and creation of an additional air layer. On the basis of the achieved results, it can be also stated that protection performance of clothing according to the EN ISO 11612:2015 can be increased from level 1 to level 2 by means of textile materials with SMA elements.
Grafting TiO2 on PMMA was studied by atom-transfer radical-polymerization (ATRP). Each step in grafting process was monitored by fourier transform infrared spectroscopy (FT-IR), 1H NMR and 13C NMR spectra. The glass temperature of grafted-PMMA film was determined by using differential scanning calorimetry (DSC). The morphology and bulk composition were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). As results, a novel method of grafting TiO2 on PMMA was successfully grafted and confirmed in various techniques. The photocatlytic activity was evaluated under UV and visible light irradiation. The reusability of TiO2-g-PMMA films was studied in details.
The combination of polyelectrolyte microgel technology with conventional functionalisation methods to activate the surface of polyester textiles is an innovative approach towards textiles adaptive to their environment. Biopolymer microgel complexes consisting of soft synthetic pH/thermo-responsive microparticles and natural polysaccharide macromolecules in various combinations serve as a novel textile surface functionalising system. Microgel incorporation into polyester surface layers can be achieved with non-demanding techniques such as UV irradiation. The adaptivity of the functionalised textiles to ambient conditions of varying pH, temperature and relative humidity is expressed by changes in their physicochemical and water management properties. These changes occur within a physiological pH/temperature range of the human body (pH 4-8, 20-40°C), owing to the corresponding stimuli-responsive properties of the functionalising microgels, giving scope for applications in the fields of biomedicine and protective clothing. Indicatively, such changes involve a shift in polyester surface charge from positive to negative values at a pH range 5.0-6.6, following the trend of the incorporated polyelectrolytes. Below 36°C, functionalised textiles exhibit improved water wettability, whilst above 36°C they have lower moisture regain and higher water vapour transmission rates than the non-functionalised textiles. The manifestation of the imparted adaptivity to ambient conditions is also a function of the intrinsic characteristics (e.g. porosity, surface roughness) of the textile, allowing for suitable combinations of substrates and functionalising systems with tailored properties.
Andrea Chiappini, Cristina Armellini, Alessandro Carpentiero, Laura Pasquardini, Lorenzo Lunelli, Alessandro Vaccari, Stefano Pelli, Anna Lukowiak, Cecilia Pederzolli, Giancarlo C. Righini, Roberta Ramponi, Maurizio Ferrari
In this paper we report on the fabrication and the characterization of colloidal systems considering complementary structures based on responsive artificial opal both in direct and inverse configuration. We will discuss alternative systems such as: (i) chromatic composite structure as chemical sensor based on polystyrene (PS) nanoparticles (NPs) embedded in elastomeric matrix, where the application of specific organic solvents produces a variation of its color; (ii) metallic dielectric structures, where the infiltration of colloidal crystals with metallic nanoparticles permits to modify the optical properties of the common opal and can be usefully exploited as SERS substrates; (iii) inverse silica opal functionalized with fluorescent aptamers in order to develop biosensors in dye labelled fluorescence detection scheme.
TiO2 films of varying mineralogical and microstructural characteristics were fabricated on sand-blasted Ti6Al4V plates by anodisation in 2 M sulphuric acid (H2SO4) and 2 M phosphoric acid (H3PO4) at 120 V and 300 mA/cm2 for 10 min and 15 min, respectively. The film formed by anodisation in H2SO4 consisted of both anatase and rutile while the film formed by anodisation in H3PO4 consisted only of rutile. This inconsistency is attributed to the presence of anatase below the level of detection in the sample anodised in the H3PO4, which consisted of a thinner TiO2 anodised film. SEM images demonstrated that H2SO4 resulted in arcing and resultant porosity while H3PO4 did not. Profilometry revealed that the former was rougher than the latter and that the latter was nearly the same roughness as the sand-blasted plate. These observations are consistent with the conclusion that H3PO4 formed a thinner anodised film and that the greater thickness from H2SO4 resulted in asperity formation, which enhanced arcing and densification. Although the anataserutile mixture and the greater roughness of the sample anodised in H2SO4 could be expected to have yielded superior performance, the fact that it did not is attributed to the greater bulk density and associated lower surface area of the TiO2 matrix. Preliminary cell culture tests showed that human osteoblast-like cells (MG63) were attached effectively on smooth anodised films (on polished plates) after 4 h of incubation while cell proliferation was confluent after 2 days. The major finding of the present work is that X-radiation in clinical doses (<200 cGy) is sufficient to cause degradation of organic species via photocatalysis.
We report on the structural characterization and the photovoltaic performances of novel photoelectric conversion materials fabricated by simplified and cheap procedures based on a chemical approach. Our prepared composite microparticles were composed of fluorosilicate/phosphorus oxide holding together by ammonium. When such composite microparticles were used in the active layer of the hybrid solar cells, the relatively high Jsc was obtained by causing the adequate carrier transport from the active layer to each electrode, attaining the best photovoltaic performance with a PCE of 4.45 %. These findings indicate that the fluorosilicate/phosphorus oxide composite microparticles have sufficient ability as the photoelectric conversion materials.
Electroluminescence offers a versatile and simple route to printed light sources. A layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was inkjet printed onto polyethylene terephthalate (PET) mesh fabrics. The conductivity–transparency relationship is determined for textile-based conductors with different thicknesses of the printed PEDOT:PSS film. Alternating current powder electroluminescent devices were made by extrusion printing a layer of phosphor onto aluminum foil and then covering this with a fabric electrode. These devices are compared with indium tin oxide (ITO) glass electrodes on a similar device. Textiles coated with conducting polymers are a potential alternative to coated polymer films for flexible, transparent conductors. The strain response of these electrodes was improved by incorporating carbon nanotubes into the conductor. These bridge cracks that form on stretching.