Solid oxide fuel cell (SOFC) is an extremely promising technology for sustainable energy conversion and storage through highly efficient electrochemical reaction at high-temperature conditions. The existing studies commonly address the final equilibrium state of the SOFC electrode reactions, giving less consideration to the micro kinetic of electrode reactions. In this paper, a kinetic model-based SOFC combined cycle power generation system is suggested to recover multiple waste heat, which includes a Kalina cycle (KC) as the bottom cycle and a Rankine cycle (RC) as the top cycle. In devneloping the proposed system, a novel kinetic model is presented for SOFC based on the microscopic mechanism of the oxygen reduction. A dynamic stochastic programming model is established to optimize the integrated system sequentially and simultaneously, with maximum power generation taken as the objective, depending on whether the SOFC system and the KC-RC system are simultaneously optimized. In sequential optimization, the output power of SOFC-KC-RC system is 320.56 kW and it is 415.04 kW using simultaneous optimization, achieving a 29.5% increase in power generation. Further comparison with the previous reports obtained by a thermodynamic model, this work leads to a 10.8% increase in power generation, showing the promising power production performance of the developed system.
In this study, we put forward a facile strategy for preparing high-performance composites utilizing epoxy resin and dodecahedral bimetallic imidazolate frameworks as the matrix resin and wear-resisting agents, respectively, with varied weight ratios via a combination of sonochemical and solution-mixing methods. The results indicate that the synthesized bimetallic imidazolate frameworks possess a dodecahedral morphology, which is composed of nickel/cobalt transition metals and imidazolium salt organic ligands, dispersing homogeneously within the resin matrix. After carefully investigating the mechanical, dry-sliding and thermal properties, we have clearly demonstrated the significance of the added bimetallic imidazolate frameworks in endowing epoxy composites with excellent wear resistance. As the filler content increases, the epoxy composites display reliable mechanical properties and thermal stabilities. Meanwhile, compared with pure resin, the wear rate is significantly reduced by 92.3%, reaching the lowest value of 0.74 × 10−5 mm3·Nm–1. Moreover, various characterizations have been carried out to reveal the wearing mechanism. This study aims to enhance the potential of bimetallic imidazolate frameworks in the applications of creating superior wear-resistant polymeric composites with satisfactory mechanical and thermal properties.
Carbon nanotubes have attracted extensive interest owing to their extraordinary properties and wide applications in many fields. Among various types of carbon nanotubes, only ultralong carbon nanotubes with macroscale lengths, low defect concentrations, and high degrees of alignment can fully demonstrate their intrinsic performance. These attributes make ultralong carbon nanotubes highly promising for applications in cutting-edge fields, such as carbon-based integrated circuits, ultra-strong fibers, and transparent conductive films. However, the mass production of ultralong carbon nanotubes with precise structural control remains a major challenge, limiting their widespread applications. In the past decades, great progress has been achieved in the study of ultralong carbon nanotubes. In this review, we summarized the growth mechanisms and the controlled synthesis strategies of ultralong carbon nanotubes. Then, we introduced the advanced applications of ultralong carbon nanotubes in many areas, such as field-effect transistors, sensors, and photodetectors. Finally, we discussed the remaining challenges and offered our perspectives on the future directions of this field.
Lithium metal anode represents the ultimate solution for next-generation high-energy-density batteries but is plagued from commercialization by side reactions, substantial volume fluctuation, and the notorious growth of lithium dendrites. These hazardous issues are further aggravated under real-world conditions. In this study, a stable Al-Li/LiF artificial interphase with rapid ion transport pathways is created through a one-step chemical pretreatment process, effectively addressing these challenges simultaneously. As a consequence, the composite interfacial layer exhibits exceptional ionic conductivity, mechanical strength, and electrolyte wettability, ensuring swift Li+ transfer diffusion while suppressing lithium dendrite growth. Remarkably, the Al-Li/LiF symmetric cell provides a cycle life exceeding 2300 h with a low polarization at 0.5 mA·cm–2. Furthermore, its enhanced cycling stability and capacity retention as well as capacity utilization stability pairing with LiFePO4 and LiNi0.8Co0.1Mn0.1O2 cathodes, highlighting the proposed approach as a promising solution for practical Li metal batteries.
With the rapid development of society, fluoride pollution in the water environment caused by human activities and natural development has constituted one of the main causes of threat to human health and safety. Among the various fluoride removal technologies available, adsorption technology has been deeply explored by various scientists and has made great progress in the current emergency situation of fluoride-contaminated water sources, especially the adsorbents containing metal or metal ion materials, which have better results. This review first describes the various mechanisms of fluoride removal by adsorption, the different methods of preparation of the materials (electrospinning, hydrothermal, solvothermal, and so on), and the current applications of the materials in fluoride removal. Then, in terms of application, the influence of different factors on the fluoride removal capacity is presented. Finally, solutions to the current problems are proposed. However, to apply them to industry for large-scale use requires the continued exploration of various researchers to make the theoretical effects into practical ones, thus improving the environment on which we depend.
Natural gas is an important resource that ensures the energy supply and reduces CO2 emissions simultaneously. However, many natural gases from well head contain a certain amount of acid gas, which must be removed to meet the pipeline requirement. Among the existing natural gas sweetening process, membrane technology is considered as a cost-effective, less energy intensive method that can remove both CO2 and H2S simultaneously. The membranes with high permeability, high selectivity, and good durability are developing very fast. In this review, we summarized the latest state-of-the-art membranes investigated for H2S/CH4 and CO2/CH4 separation applications, including conventional polymer membranes, polyimides, polymer of intrinsic microporosity, rubber polymers, carbon molecular sieve membranes, hollow fiber membranes, and membrane processes for H2S and CO2 removal from natural gas.
Supercapacitors have attracted significant attention as a promising energy storage technology due to their high power density and rapid charge-discharge capabilities. In this study, we synthesized bismuth vanadate (BiVO4) with varying molar ratios using the sol-gel combustion method and evaluated their effectiveness as supercapacitor electrodes. Crystallographic and morphological analyses confirmed the formation of nanoparticles with different phases. The vanadium-rich BiVO4 compound electrode exhibited a maximum specific capacitance of 893 F·g–1 at a current density of 0.5 A·g–1 and demonstrated superior rate capability. Additionally, an all-solid-state asymmetric supercapacitor, fabricated using vanadium-rich BiVO4 and activated carbon along with a gel electrolyte, achieved an energy density of 6.66 Wh·kg–1 at a power density of 600 W·kg–1 and sustained 86% capacitance retention after 10000 cycles. These results highlight the potential of Bi-V compounds in energy storage applications.
Efficient recycling of lithium metasilicate (Li2SiO3) from lithium-containing slag via a pyrometallurgical route demands a comprehensive understanding of its solidification process in the slag reactor. A simulation framework is developed to predict the heterogeneous phase distribution of Li2SiO3, the temperature and velocity fields considering density changes in the solidifying melt, on the apparatus scale. This framework integrates thermodynamic models via calculation of phase diagrams with the enthalpy-porosity technique and the volume of fluid method within a finite volume approach, ensuring thermodynamic consistency and adherence to mass balance. Thus, the formation of Li2SiO3 from the liquid slag composed of Li2O-SiO2 is described in space and temporal fields. Thereby, the interrelationship between the temperature field, enthalpy field, velocity field, and phase distribution of Li2SiO3 is revealed. It is shown that the lower temperature on reactor boundaries prompts the earlier formation of Li2SiO3 in the vicinity of the boundaries, which subsequently induces a downward flow due to the higher density of Li2SiO3. The predicted global mass fraction of Li2SiO3 under non-equilibrium conditions is 11.5 wt % lower than that calculated using the global equilibrium assumption. This demonstrates the global non-equilibrium behavior on the process scale and its consequences on slag solidification.
To increase the fire safety of epoxy resin, this study employed a layer-by-layer self-assembly method to prepare a biologically flame-retardant coating-modified zirconium-based metal-organic framework (chitosan/phytic acid (CS/PA) @UiO-66). This study also attempted to incorporate boron nitride (BN) to enhance the flame-retardant properties of epoxy resin composites. The results from Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy confirmed the successful synthesis of UiO-66 and illustrated the assembly of CS and PA onto UiO-66 through a self-assembly strategy. Thermogravimetric analysis in conjunction with cone calorimetry and Raman spectroscopy analyses indicated that incorporating biologically-based flame-retardant coating-modified CS/PA@UiO-66 and BN nanosheets could effectively increase the flame-retardant performance of epoxy composites. Compared with pure epoxy resin, the incorporation of CS/PA@UiO-66-3 and CS/PA@UiO-66-3/BN led to a reduction in the peak heat release rate and total heat release values of 61.13% and 22.36% for EP/CS/PA@UiO-66-3 and EP/CS/PA@UiO-66-3/BN, respectively. Notably, EP/CS/PA@UiO-66-3/BN presented a continuous and dense char layer surface with increased graphite arrangement and higher residual char content after thermal degradation and combustion, thereby providing effective suppression of heat, mass, and oxygen transfer, demonstrating promising flame-retardant efficacy. Consequently, this study successfully improved the fire safety of epoxy resin and presented a new approach for the use of biologically-based flame-retardants.
Integrating bimetallic oxides into peroxymonosulfate (PMS) based advanced oxidation processes is appealing to span the limited kinetics in view of the interaction between multiple active sites. Herein, the crednerite (CuMnO2) nanosheet, synthesized through a low-temperature hydrothermal method, has demonstrated significant potential for water remediation. The as-prepared CuMnO2 sample was characterized by involving morphology, crystal texture, and physicochemical property. The catalytic activity of CuMnO2 on PMS activation was evaluated, and the influence of PMS concentration, catalyst dosage, and pH value on the removal of bisphenol A (BPA) was investigated. Over an abroad pH range from 4.0 to 10.0, more than 90% BPA could be effectively removed after 60 min reaction with the lower dosages of 0.2 g·L–1 catalyst and 0.4 mmol·L–1 oxidant. In terms of reaction pathways, the metal (Cu/Mn)-hydroxyl moiety with cooperative effect and good redox cycle mediate the disaggregation of adsorbed PMS into surface-bound sulfate and hydroxyl radicals, which are mainly responsible for the swift elimination and mineralization of BPA in the CuMnO2/PMS system. This work provides a constructive paradigm for the development of a cost-effective heterogeneous Fenton-like reaction toward environmental purification.
