Microwave-assisted solvothermal synthesis and characterization of nanostructured Cu2SnS3 architectures

The ternary Cu-Sn-S system, as an important I-IV-VI group semiconductor with small or mid band-gap, have attracted great attention owing to broad application in photovoltaic devices and H2 evolution under visible light irradiation. In this contribution, Cu2SnS3 nanostructures were successfully synthesized by microwave-assisted solvothermal route in a short time, using CuCl2.2H2O, SnCl2.2H2O and thiourea as starting chemicals. The influence of solvent on structure, morphology and optical properties of the as-prepared samples were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy, and Raman spectroscopy. The morphology of products can be tuned from flowerlike to sphere-like by using diethyleneglycol instead of ethyleneglycol as a solvent, while the cubic crystal structure remain unchanged

Mechanical properties and Mullins effect in rubber reinforced by montmorillonite

The present work investigated the properties of rubber vulcanizates containing different nanoparticles (Cloisite 20A and Cloisite Na+) and prepared using different sonication amplitudes. The results showed that a maximum improvement in tensile strength of more than 60% over the reference sample was obtained by the nanocomposites containing 2 wt.% Cloisite 20A and 1 wt.% Cloisite Na+ and mixed with a maximum amplitude of 270 µm. The modulus at 300% elongation increased by approximately 18% and 25% with the addition of 2 wt.% Cloisite 20A and 3 wt.% Cloisite Na+, respectively. The shape retention coefficient of rubber samples was not significantly affected by the mixing amplitude, while the values of the softness measured at the highest amplitude (270 µm) were higher compared to those of mixtures homogenized with lower amplitudes. The loading-unloading and loading-reloading processes showed similar trends for all tested nanocomposites. However, they increased with increasing levels of sample stretching but were not significantly affected by filler content at a given elongation. More energy was dissipated during the loading-unloading process than during the loading-reloading. SEM micrographs of rubber samples before and after cycling loading showed rough, stratified, and elongated morphologies. XRD results showed that elastomeric chains were intercalated in the MMT nanosheets, confirming the improvement of mechanical properties. The difference between the hydrophilic pristine nanoclay (Cloisite Na+) and organomodified MMT (Cloisite 20A) was also highlighted, while the peaks of the stretched rubber samples were smaller, regardless of the rubber composition, due most probably to the decrease of interlayer spacing

Mechanical properties and Mullins effect in rubber reinforced by montmorillonite

The present work investigated the properties of rubber vulcanizates containing different nanoparticles (Cloisite 20A and Cloisite Na+) and prepared using different sonication amplitudes. The results showed that a maximum improvement in tensile strength of more than 60% over the reference sample was obtained by the nanocomposites containing 2 wt.% Cloisite 20A and 1 wt.% Cloisite Na+ and mixed with a maximum amplitude of 270 μm. The modulus at 300% elongation increased by approximately 18% and 25% with the addition of 2 wt.% Cloisite 20A and 3 wt.% Cloisite Na+, respectively. The shape retention coefficient of rubber samples was not significantly affected by the mixing amplitude, while the values of the softness measured at the highest amplitude (270 μm) were higher compared to those of mixtures homogenized with lower amplitudes. The loading-unloading and loading-reloading processes showed similar trends for all tested nanocomposites. However, they increased with increasing levels of sample stretching but were not significantly affected by filler content at a given elongation. More energy was dissipated during the loading-unloading process than during the loading-reloading. SEM micrographs of rubber samples before and after cycling loading showed rough, stratified, and elongated morphologies. XRD results showed that elastomeric chains were intercalated in the MMT nanosheets, confirming the improvement of mechanical properties. The difference between the hydrophilic pristine nanoclay (Cloisite Na+) and organomodified MMT (Cloisite 20A) was also highlighted, while the peaks of the stretched rubber samples were smaller, regardless of the rubber composition, due most probably to the decrease of interlayer spacing

On-line measurement of photocatalytic activity of powdered samples

A method for on-line measurement of photocatalytic activity of powdered samples by UV-Vis spectrometry is demonstrated. It enables photocatalytic reaction to be monitored directly in the cuvette which also serves as photocatalytic reactor. The cuvette is placed inside a double beam UV-Vis spectrometer and photocatalytic reaction is driven by LED diode mounted on homemade cuvette holder housing. Diodes can be easily changed, enable photocatalytic reaction to be performed under light of various wavelengths which is beneficial when evaluating visible-light photocatalytic activity. Another advantage of the method presented lies in the simultaneous degradation of model dye solution and monitoring of reaction kinetics, which avoid sampling during the photocatalytic reaction. Measurement of photocatalytic activity is demonstrated on degradation reaction of Methylene blue 2B as the model dye by Zn2TiO4 powder under the UV (λ ∼ 365 nm), and the visible light (λ ∼ 400 nm) and (λ ∼ 425 nm) irradiation.ERDF, European Regional Development FundMinistry of Education, Youth and Sports of the Czech Republic Program NPU I [LO1504]; European Regional Development Fund (ERDF); national budget of Czech Republic [CZ.1.05/2.1.00/19.0409]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2016/006

Impact of corrosion process of carbonyl iron particles on magnetorheological behavior of their suspensions

The study investigates an influence of carbonyl iron (CI) particles’ corrosion on magnetorheological performance of their silicone-oil suspensions. Carbonyl iron particles were oxidized thermally at 500 °C in the air or chemically in 0.05 HCl solution and the as-treated particles were subsequently used as a dispersed phase in magnetorheological suspensions. Corrosive layer on surface of oxidized particles was investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Obtained rheological data was treated with Robertson–Stiff (R–S) model to determine yield stress values and in order to find the yield stress values of prepared magnetorheological (MR) suspensions at saturation level a mathematical model was used. The suspensions based on oxidized particles showed lower values of the yield stress, which was significantly manifested at higher magnetic field intensities due to lower saturation magnetization of the particles. © 2018 The Korean Society of Industrial and Engineering ChemistryLO1504, NPU, Northwestern Polytechnical University; 17-24730S, GACR, Grantová Agentura České Republiky; MŠMT, Ministerstvo Školství, Mládeže a Tělovýchovy; CZ.1.05/2.1.00/19.0409, FEDER, European Regional Development Fund; FEDER, European Regional Development Fund; Research and DevelopmentMinistry of Education, Youth and Sports of the Czech Republic [LO1504]; Operational Program Research and Development for Innovations - European Regional Development Fund (ERDF); national budget of the Czech Republic, within the framework of the Centre of Polymer Systems project [CZ.1.05/2.1.00/19.0409]; Czech Science Foundation [17-24730S

Pressure-driven piezoelectric sensors and energy harvesting in biaxially oriented polyethylene terephthalate film

This study reports the possibility of using biaxially oriented polyethylene terephthalate (BOPET) plastic packaging to convert mechanical energy into electrical energy. Electricity is generated due to the piezoelectricity of BOPET. Electricity generation depends on the mechanical deformation of the processing aids (inorganic crystals), which were found and identified by SEM and EDAX analyses as SiO2. BOPET, as an electron source, was assembled and tested as an energy conversion and self-powered mechanical stimuli sensor using potential applications in wearable electronics. When a pressure pulse after pendulum impact with a maximum stress of 926 kPa and an impact velocity of 2.1 m/s was applied, a voltage of 60 V was generated with short-circuit current and charge densities of 15 μAcm−2 and 138 nCm−2, respectively. Due to the orientation and stress-induced crystallization of polymer chains, BOPET films acquire very good mechanical properties, which are not lost during their primary usage as packaging materials and are beneficial for the durability of the sensors. The signals detected using BOPET sensors derived from pendulum impact and sieve analyses were also harvested for up to 80 cycles and up to 40 s with short-circuit voltages of 107 V and 95 V, respectively. In addition to their low price, the advantage of sensors made from BOPET plastic packaging waste lies in their chemical resistance and stability under exposure to oxygen, ultraviolet light, and moisture.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2022/003, RP/CPS/2022/007)Ministry of Education, Youth, and Sports of the Czech Republic [RP/CPS/2022/007, RP/CPS/2022/003

Polylactide-based nonisocyanate polyurethanes: Preparation, properties evaluation and structure analysis

This study investigated the successful synthesis and characterization of nonisocyanate polyurethanes (NIPUs) based on polylactide. The NIPUs were synthesized by a condensation reaction of oligomers with hard segments (HSs) and synthesized carbamate-modified polylactic acid containing flexible segments (FSs). The oligomers with HSs were prepared from phenolsulfonic acid (PSA) or a mixture of PSA and hydroxynaphthalenesulfonic acid (HNSA), urea and formaldehyde. The mixing of oligomeric compounds with different amounts of formaldehyde was carried out at room temperature. Obtained NIPU samples with different hard segment content were tested for their mechanical and thermal properties. The tensile strength (TS) of all NIPU samples increased with an increasing amount of HSs, attaining the maximum value at an HS:FS ratio of 1:3. Samples prepared from PSA and HNSA showed higher tensile strength (TS) without significant change in elongation at break compared to the samples based only on PSA. Thermogravimetric analysis data indicated an absence of weight loss for all samples below 100 °C, which can be considered a safe temperature for using NIPU materials. Maximum degradation temperatures reached up to 385 °C. Fourier transform infrared spectroscopy results confirmed the existence of expected specific groups as well as the chemical structure of the prepared polyurethanes. DSC analysis showed the existence of two characteristic phase transitions attributed to the melting and crystallization of hard segments in the NIPU samples.Ministerstwo Edukacji i Nauki, MNiSWCentre of Polymer Systems (Tomas Bata University in Zlin, Czech Republic), within the project "Strengthening research capacity [CZ.1.05/2.1.00/19.0409, LO1504, 3269/32/P]; Polish Ministry of Science and Higher Educatio

Boosting the photoelectrochemical performance of Au/ZnO nanorods by co-occurring gradient doping and surface plasmon modification

Band bending modification of metal/semiconductor hybrid nanostructures requires low-cost and effective designs in photoelectrochemical (PEC) water splitting. To this end, it is evinced that gradient doping of Au nanoparticles (NPs) inwards the ZnO nanorods (NRs) through thermal treatment facilitated faster transport of the photo-induced charge carriers. Systematic PEC measurements show that the resulting gradient Au-doped ZnO NRs yielded a photocurrent density of 0.009 mA/cm(2) at 1.1 V (vs. NHE), which is 2.5-fold and 8-fold improved compared to those of Au-sensitized ZnO and the as-prepared ZnO NRs, respectively. The IPCE and ABPE efficiency tests confirmed the boosted photoresponse of gradient Au-incorporated ZnO NRs, particularly in the visible spectrum due to the synergistic surface plasmonic effect of Au NPs. A gradient Au dopant profile promoted the separation and transfer of the photo-induced charge carriers at the electrolyte interface via more upward band bending according to the elaborated electrochemical impedance spectroscopy and Kelvin probe force microscopy analyses. Therefore, this research presents an economical and facile strategy for preparing gradient plasmonic noble NP-incorporated semiconductor NRs, which have excellent potential in energy conversion and storage technologies.LTT20010; RP/CPS/2022/007; Tomas Bata University in Zlin, TBUMinistry of Education, Youth and Sports of the Czech Republic DKRVO [RP/CPS/2022/007]; Ministry of Education, Youth and Sports of the Czech Republic INTER-EXCELLENCE [LTT20010]; Tomas Bata University in Zli

Sonochemical synthesis of Gd3+ doped CoFe2O4 spinel ferrite nanoparticles and its physical properties

In this work, a facile and green method for gadolinium doped cobalt ferrite (CoFe2−xGdxO4; x = 0.00, 0.05, 0.10, 0.15, 0.20) nanoparticles by using ultrasonic irradiation was reported. The impact of Gd3+ substitution on the structural, magnetic, dielectric and electrical properties of cobalt ferrite nanoparticles was evaluated. The sonochemically synthesized spinel ferrite nanoparticles were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM). X-ray diffraction (XRD) study confirmed the formation of single phase spinel ferrite of CoFe2−xGdxO4 nanoparticles. XRD results also revealed that ultrasonic irradiation seems to be favourable to achieve highly crystalline single crystal phase gadolinium doped cobalt ferrite nanoparticles without any post annealing process. Fourier Transform Infrared and Raman Spectra confirmed the formation of spinel ferrite crystal structure. X-ray photoelectron spectroscopy revealed the impact of Gd3+ substitution in CoFe2O4 nanoparticles on cation distribution at the tetrahedral and octahedral site in spinel ferrite crystal system. The electrical properties showed that the Gd3+ doped cobalt ferrite (CoFe2−xGdxO4; x = 0.20) exhibit enhanced dielectric constant (277 at 100 Hz) and ac conductivity (20.2 × 10−9 S/cm at 100 Hz). The modulus spectroscopy demonstrated the impact of Gd3+ substitution in cobalt ferrite nanoparticles on grain boundary relaxation time, capacitance and resistance. Magnetic property measurement revealed that the coercivity decreases with Gd3+ substitution from 234.32 Oe (x = 0.00) to 12.60 Oe (x = 0.05) and further increases from 12.60 Oe (x = 0.05) to 68.62 Oe (x = 0.20). Moreover, saturation magnetization decreases with Gd3+ substitution from 40.19 emu/g (x = 0.00) to 21.58 emu/g (x = 0.20). This work demonstrates that the grain size and cation distribution in Gd3+ doped cobalt ferrite nanoparticles synthesized by sonochemical method, is effective in controlling the structural, magnetic, and electrical properties, and can be find very promising applications. © 2017 Elsevier B.V.Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504

Water-based indium tin oxide nanoparticle ink for printed toluene vapours sensor operating at room temperature

This study is focused on the development of water-based ITO nanoparticle dispersions and ink-jet fabrication methodology of an indium tin oxide (ITO) sensor for room temperature operations. Dimensionless correlations of material-tool-process variables were used to map the printing process and several interpretational frameworks were re-examined. A reduction of the problem to the Newtonian fluid approach was applied for the sake of simplicity. The ink properties as well as the properties of the deposited layers were tested for various nanoparticles loading. High-quality films were prepared and annealed at different temperatures. The best performing material composition, process parameters and post-print treatment conditions were used for preparing the testing sensor devices. Printed specimens were exposed to toluene vapours at room temperature. Good sensitivity, fast responses and recoveries were observed in ambient air although the n-type response mechanism to toluene is influenced by moisture in air and baseline drift was observed. Sensing response inversion was observed in an oxygen and moisture-free N2 atmosphere which is explained by the charge-transfer mechanism between the adsorbent and adsorbate molecules. The sensitivity of the device was slightly better and the response was stable showing no drifts in the protective atmosphere. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.CZ.1.05/2.1.00/19.0409; IGA/CPS/2015/006; IGA/CPS/2017/008; IGA/CPS/2016/007; LO1504, NPU, Northwestern Polytechnical University; FEDER, European Regional Development Fund; MŠMT, Ministerstvo Školství, Mládeže a Tělovýchovy; FEDER, European Regional Development Fund; Research and DevelopmentMinistry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; Operational Program Research and Development for Innovations; European Regional Development Fund (ERDF); national budget of Czech Republic [CZ.1.05/2.1.00/19.0409]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2015/006, IGA/CPS/2016/007, IGA/CPS/2017/008