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BackgroundIn molten salt reactor, the concentration of oxygen impurities in the molten salt should be strictly controlled to avoid the potential safety risks caused by the reaction of O2- in the carrier salt with UF4 fuel to generated UO2 precipitation.PurposeThis study aims to investigate the evaporation behavior of the main oxygen-containing impuritiy ions in carrier salt at high temperature and low pressure and the influence of process parameters such as temperature, pressure and initial oxygen content of molten salt on the removal of O2- in carrier salt.MethodsThe vacuum distillation method was employed and a vacuum distillation device were used to carried out experimental study of the separation behavior of the main oxygen-containing impurities NO3-, SO42-, PO43- and O2- in the carrier salt during vacuum distillation. The removal mechanism of the above ions was explored, and the specific influence of process conditions on the separation effect of O2- distillation was investigated.ResultsThe results show that the removal ability of oxygen-containing impurities by vacuum distillation is NO3-＞PO43-＞SO42-＞O2-. The removal capacity of O2- increases with the increase of temperature, and the recovered salt with a total oxygen content about 2.40×10-4 g·g-1 salt is obtained at 1 050 ℃. The phenomenon of oxygen with a total oxygen content about 2.50×10-4 g·g-1 salt is observed when the pressure is higher than 40 Pa. The oxygen entrainment is increased during the evaporation of molten salt with the decrease of pressure, and the recovered salt content in the recovered salt continued to decrease with the decrease of the initial content of O2- in the carrier salt, which confirmed the technical feasibility of melting salt multiple distillation to remove oxygen.ConclusionsIt is verified by study shows that vacuum distillation can remove oxygen-containing impurities from carrier salt effectively and achieve the rapid and efficient purification of the carrier salt.

Doping W into Li can greatly enhance the activity of Li-ion battery. However, the structures and properties of W-doped Li clusters remain elusive. In this study, we combined the global-minimum optimization and the density-functional theory calculations to systematically explore the lowest-energy structures of WLin (n = 2–12) bimetallic clusters and found it evolves from a triangle structure to a polyhedron pyramid structure, and finally to an endohedral cluster with W atom inside. In particular, W@Li12 is identified as a superatom. The cluster exhibits an icosahedral structure with 18 valence electrons, which has a notable HOMO–LUMO gap of 1.56 eV. The ab initio molecular dynamics simulations confirm the thermal stability of this cluster. Furthermore, the infrared spectrum has two vibration peaks, corresponding to the bending vibration and stretching vibration of the tungsten–lithium bond, respectively. The UV–Vis spectrum has two absorption peaks at the excitation energy of 2–4 eV, revealing the characteristics of the orbital electron transition. This study paves the way for the study of Li–W alloy to understand its mechanism in Li-ion battery. [ABSTRACT FROM AUTHOR]

The vapor-fed passive DMFC is highly energy-dense, environmentally friendly, and noise-free. However, controlling the internal environment of the DMFC, especially temperature and humidity, is challenging due to the lack of heat/water management system. To address this issue, we propose an alveolus-inspired flow field in the DMFC cathode, which is 3D printed to maintain the internal environment similar to that of alveolus. Our findings show that the alveolus-inspired flow fields with upward and leftward pores exhibit higher and more stable DMFC performance (20.3 mW cm−2), which is 2.2 times that of the traditional DMFC. This is due to the similar characteristics of the alveolus in the lung, which maintains an excellent and stable internal environment with higher humidity and temperature (compared to traditional DMFC increases of greater than 10 °C). Moreover, as the partially open chambers are similar to those in the alveolus, the biomimetic DMFC can resist harsh weather conditions such as strong winds, sand, and dust. Specifically, after sand and dust treatment, the performance of the biomimetic DMFC decreased only by 16.6%, while that of the traditional DMFC sharply decreased by 66.6%. This alveolus-inspired flow field can be applied to other air-breathing fuel cells or batteries, such as hydrogen–air fuel cells, zinc–air batteries, lithium–air batteries, etc., to improve their performance, stability, and harsh weather resistance. [ABSTRACT FROM AUTHOR]

A dissolved oxygen sensor was developed based on time‐domain lifetime measurement with an oxygen sensing film. The oxygen sensing film was fabricated by embedding PtOEP in a highly stable and highly hydrophobic fluorinated matrix synthesized from methacrylate, fluorinated methacrylate, and 3‐(tris(trimethylsilyloxy)silyl)propyl methacrylate via free radical polymerization. The fluorinated methacrylate provided the high stability and the 3‐(tris(trimethylsilyloxy)silyl)propyl methacrylate provided the extra hydrophobicity. The PtOEP was excited using pulsed signals from a green‐light LED and the fluorescence lifetime was evaluated by time‐domain lifetime measurement. The dynamical quenching of fluorescence response by dissolved oxygen was calibrated using the Stern‐Volmer plot with a high τ0/τ100 ratio of 5.68 and a Stern‐Volmer constant of 0.112 mg−1 dm3. It was demonstrated that the dissolved oxygen sensing film showed high stability under the varied excitation intensity and long‐term stability in the accelerated aging experiment and the repeated freeze‐thaw‐cycling tests. [ABSTRACT FROM AUTHOR]

Proton exchange membrane (PEM) is pivotal for proton exchange membrane fuel cells (PEMFCs). In the present work, a block copolymer with hydrophilic alkyl sulfonated side groups and hydrophobic flexible alkyl ether side groups, poly(5'‐hexyloxy‐1',4‐biphenyl)‐b‐poly(2',4'‐bispropoxysulfonate‐1',4‐biphenyl) (HBP‐b‐xBPSBP), is designed and synthesized by copolymerization of the hydrophilic and hydrophobic oligomers. The oligomers are synthesized via a Pd‐catalyzed Suzuki cross‐coupling of 1,3‐dibromo‐5‐hexyloxybenzene, and 3,3'‐[(4,6‐dibromo‐1,3‐phenylene)bis(oxy)]bis(propane‐1‐sulfonate) or 1,4‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)benzene. The good solubility and film‐forming characteristics are achieved via the introduction of flexible hexyloxy side groups, and high ion exchange capacity (IEC) is achieved via the introduction of high density of alkyl sulfonated side groups. The HBP‐b‐0.5BPSBP has the highest IEC of 3.17 mmol/g, the highest proton conductivity of 43.5 mS/cm at 95 °C and 90% relative humidity (RH) and low methanol permeability of 6.45×10−7 cm2/s. Meanwhile, crosslinked HBP‐b‐xBPSBP exhibits promising water uptake, swelling ratio and low methanol permeability. These characteristics are attributed to the crosslinked structure and the hydrophilic/hydrophobic nanophase separation morphology promoted by the poly(m‐phenylene) main chains, flexible alkyl ether groups, and alkyl sulfonated side groups. [ABSTRACT FROM AUTHOR]