Materials Science for Energy Technologies最新文献

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.

In just a few years, the worldwide scientific community has worked diligently to increase the photovoltaic conversion efficiency of perovskite solar cells from 3.8% to 25.7%. Due to its low stability and poor scalability, it still lags in commercial performance concerning the crystalline silicon solar cell. Most of the high-efficiency perovskite solar cells (PSC) reported in the literature are on a 0.01 cm² area, and the efficiency of PSC decreases with an increase in area. The maximum said stability to date is 10,000 h which is relatively low compared to crystalline silicon technology. This work discussed the causes of instability, degradation mechanism, scalable fabrication methods, and high-stability perovskite solar cell. It emphasised the need for setting up testing protocols for universal stability testing of perovskite solar cell technology. The study found that trap states in the absorber layer, hole transport layer (HTL), and electron transport layer (ETL) are the reason for lower stability. The lower dimension perovskite solar cell shows better stability compared to its 3D counterparts.

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 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.

Agricultural waste is rich in organic matter and an important secondary source of phosphorus, which can be converted into valuable products through various technologies. Composting is an effective way to treat agricultural waste and further produce organic fertilizer, achieving waste minimization and stabilization. This paper reviews the current situation of agricultural waste pollution and composting technology, introduces the parameters that influence of the composting process and the optimal conditions, and presents the indicators for evaluating the decay of compost products and the evaluation criteria as well. In the composting process, small-molecule organic acids produced by the degradation of easily degradable organic matter such as sugars and lipids and various enzymes produced by microorganisms (phytase, phosphatase, etc.) can mineralize organic phosphorus such as phytate and phospholipids, promote phosphorus activation and provide phosphorus sources for microorganisms, so the conversion of organic matter and phosphorus is related to the fertilizer effect of composted products. Therefore, the clarification of the characteristics of organic matter and phosphorus transformation in the composting process is an important prerequisite for the resource utilization of agricultural organic waste. This paper provides theoretical support for the sustainable utilization of agricultural organic waste resources.

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.

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.

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.