Materials Science for Energy Technologies最新文献

Organic redox flow batteries have attracted a lot of interests both in academics and industries. Accordingly, many organic materials and chemistries have been studied, providing a solid foundation for development of low-cost organic flow batteries. However, capacity loss/fade as a result of organic molecule decomposition/degradation is a major hindrance towards further advancement of this promising, sustainable and large-scale energy storage technology. Understanding the causes of decomposition as well as its mechanism is thus necessary to unravel this major challenge. Therefore, this perspective/views focus on highlighting the different methods that can be employed for decomposition assessment of organic molecules in flow battery systems. This will help in engineering and designing stable electroactive organic molecule to enable development of durable and long cycle life redox flow battery.

The composite Ni-SDC cathode is a key element in the formulation of the hybrid MCFC/SOFC system. It must encompass electrical and ionic conductivity, high catalytic activity to allow for the reduction of oxygen and the oxidation of carbon dioxide and provide high permeability for gaseous reactants. This requires not only a specific chemical composition but also the microstructure has to be designed and specifically manufactured.

These studies present the thermal treatment process and resultant properties of Ni-SDC cathodes with various SDC volume fractions. A new procedure for producing the Ni-SDC cathode was optimized based on the reference sintering process for pure Ni, modifying the temperature profile as well as the atmospheric gas composition (air, nitrogen, nitrogen + hydrogen mixture) and the sintering temperature (800°C, 900°C, 1000°C). This was done using thermogravimetric analysis (TGA) and electron microscopy (SEM).

The research results show that the addition of SDC, with a specific atmospheric formulation, facilitates the organic phase decomposition. It has been observed that an increase in sintering temperature enhances mechanical strength and improves electrical conductivity.

The molecule-water and molecule–molecule interactions are the main keys to understanding the behavior of polysaccharides in an aqueous solution. In this work, electrical impedance spectroscopy is used to investigate raw polysaccharides' dielectric and electrical properties. Impedance data were carried out for different concentrations in the frequency range [10^-2–10⁶Hz] and then analyzed in Nyquist and bode representation, revealing one clear maximum due to the electrode polarization. Therefore, the complex conductivity is analyzed and makes the other relaxation processes very clear.

Moreover, an appropriate equivalent circuit was developed, showing good agreement with the experimental data. The extrapolation and deconvolution approaches in the frequency range [10^-3–10⁷Hz] were performed to confirm the presence of the three relaxation processes and the validity of the equivalent circuit. The first was attributed to the electrode polarization, and the other processes were attributed to the molecules-water and molecule-counterion interactions. Finally, a clear transition at 5% (w/v) is shown in the evolutions of the conductivity, suggesting the transition from the dilute to the semi-dilute domain.

Previous studies have shown that co-doping of BST resulted in enhanced dielectric properties of BST. Meanwhile, no work was reported about effect of Mo, Se on the dielectric properties of Barium strontium titanate (BST). Hence, this report was expected to contribute on the ways of enhancing the dielectric activity of BST through doping. The purpose of the research was to investigate the microstructural, morphological as well as the dielectric properties of BST and Mo, Se co-doped BST following their slow injection sol–gel synthesis and calcined at 800 °C. The effective synthesis of cubic Ba_0.6(Sr_0.4-xSe_x)(Mo_yTi_1-y)O₃ nanopowder has been confirmed using FT-IR, Raman spectroscopy, EDS, and XRD techniques where the presence of every element and the empirical formula matched with the predicted ones. The average crystallite size of BST increased from 23.97 nm to 26.18 nm after doping. Likewise, the average grain size elevated from 40.13 nm to 53.27 nm accompanied by the elevation of the number of agglomerated crystallites in a grain per SEM particle (1.98 to 3.55). The average particle size of Mo and Se co-doped BST was found as 26.63 nm. The lowering of pore size as well as pore volume of BST was also observed after doping. All these properties led to the elevation of dielectric constant (from 248.8 to 953.00) and lowering of the dielectric loss (from 0.1620 to 0.0928). Therefore, the Mo, Se co-doped BST possessed such varied properties from BST which makes it to be effectively utilized in capacitive applications such as supercapacitors.

The synthesis of graphene nanosheets (GNs) from sub-bituminous coal aims to increase the added value of coal in a cheap, easy and proclaimed this method on an industrial scale. The addition of biocatalyst (BFS) in the pyrolysis process can reduce the reactive temperature of the pyrolysis process so that the combustion reaction runs better at low temperatures of 200-300℃. Followed by hydrothermal carbonization of coal at 180℃ for 6 h with the addition of pyrolysis liquid smoke. Filter the results and exfoliate using 24 kHz ultrasonication for 30 min. Then centrifuge at 10,000 rm for 10 min to separate the solids. Wash the solids with deionized water to obtain a neutral pH. Using FESEM and TEM to obtain the morphological characteristics of GNs, structural characterization was studied using XPS, FTIR, and XRD. The GNs produced using BFS yielded 7–8 layers of Graphene, and a crystal size of 2.7 nm showing promising efficiency from the methodology used.

Energy efficiency in the building sector has attracted a great deal of interest in recent years; because it is seen as a potential solution to minimize the high energy consumption caused by the acceleration of the urbanization process. Several methodologies have been developed to assess the energy performance of buildings, including the energy signature, which is an empirical tool used to represent the real energy performance of buildings. Synthetic data of energy consumption of buildings are generated by ECOTECT simulation program, which is a class of energy models that uses characteristic data (dimensional, physical and location) of the building to predict energy consumption. The primary goal of this research is to examine how solar rays and occupants affect a residential building's energy signature in Errachidia, a city in the southeast of Morocco characterized by its arid climate. The results show that when solar radiation was taken into account, the outcomes of the building's intrinsic characteristics (a and b) enhanced the signature. The distinct response in energy use serves as justification. In fact, the solar radiation provides a significant improvement with an important R² accuracy of about 0.999. Moreover, the introduction of the occupancy factor has a significant impact on energy savings and temperature fluctuations in energy consumption. The importance of parameter b related to the fixed loads of the building is more influenced by the occupancy factor. This opens up a new possibility for energy-saving studies in the case of an arid climate.

Current trends suggest that as manufacturing and energy demand increase, there will be a greater consumtion for energy storage, requiring its utilization for days, weeks, or even months in the future. Recent studies also need to be conducted on binders that could support electrode performance, considering that binders are also a crucial component of the electrochemical processes in cells. In this study, activated carbon-based supercapacitor electrodes were fabricated using three different binders: PVDF, SBR, and LA133. With a gravimetric capacitance and power density of 52.57 Fg⁻¹ and 92.64 W.kg⁻¹, and a lifetime up to 87.23% after 1000 cycles, AC/CB LA133 has the best performance. LA133 was used as a binder to generate a Ni/Si composite as a battery electrode combined with the AC/CB LA133 supercapacitor to fabricate a supercapattery. This clearly shows that when a suitable binder such as LA133 is used, the electrochemical performance could be improved.

The pollution of water with heavy metals is one of the most important health and economic problems globally. Therefore, the green preparation of Cu²⁺ nanoparticles from avocado seed extract can provide a method of adsorbing these heavy metals at the lowest cost and easily and safely. In addition, our research was motivated by the ability of these nanoparticles to inhibit some types of bacteria. In this study, seed extract was prepared and then reacted with copper²⁺ solution to obtain nanoparticles using the biosynthesis method. These nanoparticles were diagnosed by means of the FESEM, XRD, AFM, UV–vis, and FTIR techniques. FESEM images showed Cu peaks at about 1 and 9 keV of a crystal nature. The crystal size was 62.25 nm, according to the XRD results. The AFM images showed that the spherical particles had an average height of 21.289 nm. AUV–vis absorption band was observed at 530 nm, indicating copper²⁺ nanoparticles. The FTIR spectra showed the interaction of the seed extract with Cu²⁺ ions via a reduction reaction. The synthesized copper²⁺ nanoparticles demonstrated the inhibition of bacterial activity when used against E. coli and Staphylococcus aureus. Copper nanoparticles were used as a surface adsorbent for cadmium²⁺ ions of contaminated water, and the nanoparticles showed an active role.

Lithium-borate-based glass co-doped with nickel and cobalt ions was successfully fabricated by a two-step melt quenching method. The relationship between Ni and Co contents in the glasses was investigated, with a focus on their electrochemical properties and battery performance. Cyclic voltammetry was used to pre-investigate the electrochemical properties of the glass electrodes. It was found that the specific capacitance of all conditions was above 100 F/g. This preliminary study showed that the glass is feasible to use as a Li-ion battery cathode. The Co-rich content sample (NC11) exhibited the highest specific capacity of 380 mAh/g in the first cycle test. However, the specific capacity was dramatically decreased in subsequent cycles due to Li-ion trapping in the glass structure. Additionally, the higher amount of Ni ions in the co-doping Ni/Co-LBO glass enhanced the retention properties. This suggests that Ni-rich content could improve the release of free Li-ions from the host glass structure.