Search

Možnosti ekologické syntézy přilákaly enormní zájem o výzkum jako alternativu nebezpečných chemikálií. Pozoruhodné vlastnosti ekologicky syntetizovaných materiálů zahrnují šetrnost k životnímu prostředí, vysokou hojnost, antimikrobiální, antioxidační a biologickou odbouratelnost. Integrace ekologicky syntetizovaných materiálů do elektronických zařízení nejen zvyšuje ekonomický přínos přírodních odpadních zdrojů, ale také šetří naše životní prostředí. Tento článek se zabývá současným výzkumným úsilím v oblasti trendů v oblasti ekologicky syntetizovaných materiálů, výzev a jejich potenciálních aplikací v senzorech, akčních členech, skladování energie a výrobě energie. Green synthesis methods have attracted enormous research interest as replacements for dangerous chemicals due to their abundance and eco-friendliness. The remarkable properties of green synthesized materials include environmental friendliness, high abundance, antimicrobial, antioxidant and biodegradability. The integration of green synthesized materials in electronic devices not only enhances the economic benefit of natural waste resources but also conserves our environment. This review article is dealing with the current research efforts in green synthesized materials trends, challenges and their potential applications in sensors, actuators, energy storage and energy generation.

Microcapsules consisting of paraffin wax cores with a melting point of approximately 42 °C and a melamine-formaldehyde resin shell were synthesized using in situ polymerization. These microcapsules have a uniform distribution with a spherical shape and an average diameter of approximately 15 μm. The thickness of the shell was approximately 1.5 μm. Shape-stabilized phase change materials (PCM) based on high-density polyethylene (HDPE) mixed with micro-encapsulated paraffin wax were prepared and investigated for application in thermal energy storage. The distribution of the capsules within the HDPE matrix was uniform without any tendency toward agglomeration. The microencapsulated paraffin wax acts as a high-latent-heat material, whereas the HDPE matrix ensures the compact shape, structural compactness and mechanical strength of the final PCM. The periodic temperature method was used to determine the thermal conductivity and thermal diffusivity of the phase change materials. A guarded hot plate unit was used to determine the latent heats of these phase-change materials. The thermal conductivity and diffusivity of the investigated PCMs decreased as the microcapsule content increased. In contrast, the latent, sensible and total heat of the PCMs increased with the paraffin content.

The results of investigation on the ageing of ceramic manganites La1-cSrcMn0.90Ni0.05Ge0.05O3+γ and La1-cSrcMn0.90Zn0.05Ti0.05O3+γ (c = 0.15, 0.17, 0.19) during long-term storage at normal conditions are presented. Unit cell volume of all manganites having rhombohedral structure decreased over time. The width of X-ray diffraction reflexes from (Ni,Ge)-compositions varied irregularly within the measurement error, and the width of reflexes from (Zn,Ti)-contained manganites decreased significantly. Magnetization of all samples increased in the end of storage period. Curie point of compositions with c > 0.17 exhibited some trend of increase. Ageing leaded to the lowering of “metal-semiconductor” transition temperature in (Ni,Ge)-substituted manganites. (Zn,Ti)-contained compositions showed only semiconductor behavior in investigated temperature range from 100 to 300 K, and the changes of their magnetic parameters were most considerable. The increase in magnetization and Curie point reached 7.5 % and 11 %, respectively. Possible mechanisms of ageing in considered materials are discussed in terms of oxidation processes, formation of microinhomogeneities and relaxation of internal stresses.

The efficient storage of energy combined with a minimum carbon footprint is still considered one of the major challenges towards the transition to a progressive, sustainable and environmental friendly society on a global scale. The energy storage in pure chemical form using gas carriers with high heating values, including H-2 and CH4, as well as via electrochemical means using state-of-the-art devices, such as batteries or supercapacitors, are two of the most attractive alternatives for the combustion of finite, carbon-rich and environmentally harmful fossil fuels, such as diesel and gasoline. A few-step, reproducible and scalable method is presented in this study for the preparation of an ultra-microporous (average pore size around 0.6 nm) activated carbon cloth (ACC) with large specific area ( GT 1200 m(2)/g) and pore volume (similar to 0.5 cm(3)/g) upon combining chemical impregnation, carbonization and CO2 activation of a low-cost cellulose-based polymeric fabric. The ACC material shows a versatile character towards three different applications, including H2 storage via cryo-adsorption, separation of energy-dense CO2/CH4 mixtures via selective adsorption and electrochemical energy storage using super-capacitor technology. Fully reversible H-2 uptake capacities in excess of 3.1 wt% at 77 K and similar to 72 bar along with a significant heat of adsorption value of up to 8.4 kJ/mol for low surface coverage have been found. Upon incorporation of low-pressure sorption data in the ideal adsorbed solution theory model, the ACC is predicted to selectively adsorb about 4.5 times more CO2 than CH4 in ambient conditions and thus represents an appealing adsorbent for the purification of such gaseous mixtures. Finally, an electric double-layer capacitor device was assembled and tested for its electrochemical performance, constructed of binder-free and flexible ACC electrodes and aqueous CsCl electrolyte. The full-cell exhibits a gravimetric capacitance of similar to 121 F/g for a specific current of 0.02 A/g, which relative to the ACCs specific area, is superior to commercially available activated carbons. A capacitance retention of more than 97% was observed after 10,000 charging/discharging cycles, thus indicating the ACCs suitability for demanding and high-performance energy storage on a commercial scale. The enhanced performance in all tested applications seems to be attributed to the mean ultra-micropore size of the ACC material instead of the available specific area and/or pore volume.

Porous activated carbon or nanostructured carbon materials have a promising future as hydrogen storage media. The hydrogen storage capacity of nanostructured carbon materials can be further enhanced by spillover of atomic hydrogen from a supported catalyst. In the present work, both of these factors have been put to test to study the hydrogen storage capacity of palladium (Pd) nanoparticles dispersed over the surface of functionalized hydrogen-exfoliated- graphene (Pd/f-HEG). The high-pressure hydrogen storage measurements of HEG and Pd/f-HEG show a hydrogen storage capacity of 0.5 and 1.76 wt % respectively at 25 �C and 2 MPa pressure. Functionalization of graphene facilitates uniform dispersion of Pd nanoparticles, which result in an increased hydrogen storage capacity of graphene by 69%. Heats of adsorption have been calculated for HEG and Pd/f-HEG that are consistent with the theoretical calculations from literature and provide an experimental evidence for the spillover effect. � 2011 American Chemical Society.

Minimization of total weight is the major criterion in the design of a solid state hydrogen storage device for mobile or portable applications. The design should also address the requirements such as storage capacity, charge/discharge rates, space constraints, coolant temperature and hydrogen supply pressure. To achieve this, one should be able to reliably predict the dynamic performance of the storage device. In this paper, a parametric study of hydrogen sorption in an air-cooled annular cylindrical hydrogen storage device with external fins is reported. LaNi 5 , which has excellent hydrogen storage properties is used as the hydriding material. The influence of different geometric parameters such as hydride bed thickness and fin height, and operational parameters such as hydrogen supply pressure and cooling air temperature are studied. Copyright , Manchester University Press.

Structured porous materials have provided several breakthroughs that have facilitated high rate capability, better capacity retention and material stability in Li-ion batteries. However, most advances have been limited to half cells or lithium batteries, and with a single mode of charge storage (intercalation, conversion, or alloying etc.). The use of dual-mode charge storage with non-traditional material pairings, while maintaining the numerous benefits of nanoscale materials, could significantly improve the capacity, energy density, stability and overall battery safety considerably. Here, we demonstrate an efficient, high capacity full inverse opal Li-ion battery with excellent cycle life, where both the cathode and anode binder-free electrodes are composed of 3D nanocrystal assemblies as inverse opal (IO) structures of intercalation-mode V2O5 IO cathodes and conversion-mode Co3O4 IO anodes. Electrochemically charged Co3O4 IOs function as Li-ion anodes and the full V2O5/Co3O4 cell exhibits superior performance compared to lithium batteries or half cells of either IO material, with voltage window compatibility for high capacity and energy density. Through asymmetric charge–discharge tests, the V2O5 IO/Co3O4 IO full Li-ion cell can be quickly charged, and discharged both quickly and slowly without any capacity decay. We demonstrate that issues due to the decomposition of the electrolyte with increased cycling can be overcome by complete electrolyte infiltration to remove capacity fading from long term cycling at high capacity and rate. Lastly, we show that the V2O5 IO/Co3O4 IO full Li-ion cells cycled in 2 and 3-electrode flooded cells maintain 150 mA h g−1 and remarkably, show no capacity fade at any stage during cycling for at least 175 cycles. The realization of an all-3D structured anode and cathode geometry with new mutually co-operative dual-mode charge storage mechanisms and efficient electrolyte penetration to the nanocrystalline network of material provides a testbed for advancing high rate, high capacity, stable Li-ion batteries using a wide range of materials pairings.

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2@MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2. The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2@MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2@MoSe2, thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures. A controlled synthesis of lattice-mismatched core-shell TiO2@MoS2 nano-onion heterostructures is developed, using unilamellar Ti0.87O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2. The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The core-shell TiO2@MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Scopus

A novel, one-step, wet-free, environmental friendly and high-yield method for producing few-layer graphene powders with large surface areas (up to 800 m2/g) and narrow nanopore sizes (0.7-0.8 nm) using plasma-induced exfoliation of natural graphite is presented. Advanced characterization techniques were employed, including scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and N2 gas adsorption/desorption measurements at 77 K, to investigate the morphological, elemental, structural and textural/porosity properties of these nanomaterials. Fully reversible H2 gas adsorption/desorption isotherms with maximum gravimetric capacities of up to ∼2 wt.% at 77 K and ∼60 bar are reported here. The H2 storage performance at 77 K is well correlated with certain textural features such as specific surface area and microporosity. The results of this work provide a valuable feedback for further research on plasma-processed graphene-based materials towards efficient H2 storage via cryo-adsorption. © 2016 Elsevier Inc. All rights reserved. 225 482 487 482-487

RGO/Sb2S3 nanocomposite has been investigated in this study as a dual anode material for Li- and Na-ion battery applications. The stibnite phase of Sb2S3, and its rGO composite have been obtained from a molecular complex, Sb(SCOPh)3 or its rGO mixture by solid state decomposition or hydrothermal treatment. The pristine sample consists of micron sized particles with rod-like morphology while the rGO composite is made of nanoparticles of Sb2S3 embedded in rGO sheets. Electrochemical lithium and sodium storage properties of the prepared materials have been investigated using galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy studies. The rGO composite demonstrates better lithium storage capacity than the pristine sample owing to enhanced conductivity. In addition, the rGO sheets act as a buffer for volume change during lithium/sodium cycling resulting in a better energy storage. 2016 American Chemical Society. J.J.V. thanks the Ministry of Education, Singapore, through NUS Tier 1 FRC grant (No. R143-000-562-112). M.V.R. would like to thank the National Research Foundation (NRF), Singapore, for the research Grant no. WBS:R-284-000-115-281. Scopus

cited By 3; International audience; Adsorption properties of gram-scale samples of different kind of arc discharge nanotubes were studied, namely: (A) raw collaret collected on the cathode, (B) raw soots collected on the lateral reactor wall, (C) thermally treated soot, and (D) thermally then chemically treated soot. The morphology, structure, and composition of these materials were characterized by SEM, TEM, TGA, and BET. In addition, hydrogen adsorption isotherms were recorded experimentally for A, B, and D samples over the pressure range of 0 to 55 bar at ambient temperature. Our experiments indicated a maximum - yet weak - hydrogen storage at room temperature of ∼0.13 H 2 wt% for the purified product (D). Copyright © 2007 American Scientific Publishers All rights reserved.

Background Magnesium alloys are recommended as a potential material for osteosynthesis. It is known that storage-induced property modifications can occur in materials like aluminum. Thus the aim of this study was to analyze the influence of storage durations of up to 48 weeks on the biomechanical, structural, and degradation properties of the degradable magnesium alloy LAE442. Methods Extruded implants (n = 104; Ø 2.5 mm × 25 mm) were investigated after storage periods of 0, 12, 24, and 48 weeks in three different sub-studies: (I) immediately after the respective storage duration and after an additional (II) 56 days of in vitro corrosion in simulated body fluid (SFB), and (III) 48 weeks in vivo corrosion in a rabbit model, respectively. In addition, the influence of a T5-heat treatment (206 °C for 15 h in an argon atmosphere) was tested (n = 26; 0 week of storage). Evaluation was performed by three-point bending, scanning electron microscopy, radiography, µ-computed tomography, evaluation of the mean grain size, and contrast analysis of precipitations (such as aluminum or lithium). Results The heat treatment induced a significant reduction in initial stability, and enhanced the corrosion resistance. In vivo experiments showed a good biocompatibility for all implants. During the storage of up to 48 weeks, no significant changes occurred in the implant properties. Conclusions LAE442 implants can be safely used after up to 48 weeks of storage.

Latent heat thermal storage systems (LHTS) utilize their latent heat capacity to dissipate high heat fluxes while maintaining quasi-isothermal conditions. Phase change materials (PCMs) absorb a large amount of energy during their phase transformation from solid to liquid, maintaining quasi-isothermal conditions. However, they are often beset with low thermal conductivities which necessitate the use of a thermal conductivity enhancer (TCE) as it is impossible to design a device that can completely avoid sensible heat in the premelting or postmelting phase. In this study, the heat transfer performance of LHTS with cross plate fins as a TCE is numerically investigated for different values of fin thicknesses and fin numbers along the length and breadth. A hybrid artificial neural network coupled genetic algorithm (ANN–GA) is then used to obtain the optimized dimensions for the composite heat sink with cross plate fins as TCE for a fixed volume and a specific heat flux input. The numerically optimized configuration is finally validated with in-house experiments.

The goal of this study is to propose a cost-effective method for the optimization of the ex situ carbonation of basaltic rocks. The ball milling process was applied to a sample of olivine basalt from the Troodos ophiolite complex (Cyprus) for the first time, in order to fabricate novel nanomaterials for CO2 storage. The purpose was to accelerate the kinetics of rock–fluid reactions during the carbonation procedure. Various methodologies were used for the characterization of the starting rock material and the ball-milled samples. Preliminary results reveal that only a few hours of wet ball milling with ethanol as process control agent can induce significant changes to olivine basalt towards improvement of its performance for CO2 storage. Specifically, CO2 uptake measurements via the use of the temperature-programmed desorption (TPD) technique indicate that 4h of ball milling with 50wt.% ethanol can lead to an enhancement of the carbonation of olivine basalt by 295%. The experimental results strongly suggest that (i) olivine basalts have important CO2-storage capacity and are very promising lithotypes for ex situ carbonation, and (ii) the ball milling process provides hopes for its use at an industrial scale as a preparation technique for the safe and permanent ex situ storage of CO2. •The ball milling process was used to create novel nanomaterials for CO2 capture.•The experiments were carried out using a sample of olivine basalt.•Olivine basalt shows higher CO2 uptake compared to the reference forsterite.•The pore volume principally controls the extent of carbonation.•Ball milling results in an enhancement of the carbonation of olivine basalt by 295%. 273 220 229 220-229

Pd on nitrogen rich carbon material g-C3N4 has been synthesized by a simple cost-effective method. From the study of the hydrogen storage properties of host g-C3N4 matrix and Pd-g-C3N4 by pressure reduction method using Sievert's apparatus in the ranges 0.1 ? PH2(MPa) ? 4 and 0 ?T(�C) ? 100, it has been demonstrated that the hydrogen storage capacity of Pd-g-C3N4 reaches 2.6 wt% at 25 �C and 4 MPa. At room temperature, an increase of 66% in the hydrogen uptake capacity is accounted by Pd nanoparticles (Pd-NPs) decoration over host g-C3N4 matrix, clearly demonstrating the hydrogen spillover process. The good dispersion of Pd-NPs over host g-C3N4 matrix and strengthened interaction between the host g-C3N4 matrix and Pd-NPs catalyze the dissociation of hydrogen molecules and subsequent migration of hydrogen atoms to the host g-C3N4 matrix due to spill over mechanism. From the present study, it can be concluded that the nexus between the catalyst support and catalyst particles results in the high hydrogen uptake capacity. � 2014 Hydrogen Energy Publications, LLC. All rights reserved.

Hydrogen has been widely recognized as the "Energy Carrier" of the future. Efficient, reliable, economical and safe storage and delivery of hydrogen form important aspects in achieving success of the "Hydrogen Economy". Gravimetric and volumetric storage capacities become important when one considers portable and mobile applications of hydrogen. In the case of solid state hydrogen storage, the gas is reversibly embedded (by physisorption and/or chemisorption) in a solid matrix. A wide variety of materials such as intermetallics, physisorbents, complex hydrides/alanates, metal organic frameworks, etc. have been investigated as possible storage media. This paper discusses the feasibility of lithium- and sodium-aluminum hydrides with emphasis on their thermodynamic and thermo-physical properties. Drawbacks such as poor heat transfer characteristics and poor kinetics demand special attention to the thermal design of solid state storage devices. � 2014 Elsevier Ltd. All rights reserved.

Energy provision and storage are significant and critical issues for wireless sensor network (WSN) applications. Hybrid energy devices incorporating energy harvesting and storage requires the development of enhanced energy storage materials and architectures. A decreased footprint with the same energy capability is desirable to maximise the energy density and enable long-life wireless sensors. Methods to structure active and support battery materials enhance the device characteristics offering mechanical and electrical support. The results below are for materials that can be processed in 3D or 1D to decrease the footprint of the energy storage element. The effect of the support material is also shown to be significant and directly relevant for high aspect ratio nanostructure where the lithium active materials experience volume changes during charge and discharge.

`Electronic nose' applications have been increasing in number in recent years. The reliability of these applications is mainly based on the selectivity properties of the sensors composing the array and on the stability of their characteristics. In this paper an electronic nose based on metalloporphyrins-coated quartz microbalance sensors is described. Due to the nature of the chosen metals, the sensors are particularly suitable to classify environments in which compounds containing donor atoms, such as amines, alcohols and sulphides, play a key role. The aroma of fish during storage is one of these environments. The array has been applied both for classification and for identification of the degree of freshness of stored cod fish. Data on the recognition of storage days and continuous short time monitoring are reported and discussed. Results of the electronic nose response are displayed by a method that is based on the parametrization of the input temporal evolution and allows an adequate representation of the evolving chemical environment.