Antimony (Sb)-based anode materials have recently aroused great attention in potassium-ion batteries (KIBs), because of their high theoretical capacities and suitable potassium inserting potentials. ...Nevertheless, because of large volumetric expansion and severe pulverization during potassiation/depotassiation, the performance of Sb-based anode materials is poor in KIBs. Herein, a composite nanosheet with bismuth–antimony alloy nanoparticles embedded in a porous carbon matrix (BiSb@C) is fabricated by a facile freeze-drying and pyrolysis method. The introduction of carbon and bismuth effectively suppress the stress/strain originated from the volume change during charge/discharge process. Excellent electrochemical performance is achieved as a KIB anode, which delivers a high reversible capacity of 320 mA h g–1 after 600 cycles at 500 mA g–1. In addition, full KIBs by coupling with Prussian Blue cathode deliver a high capacity of 396 mA h g–1 and maintain 360 mA h g–1 after 70 cycles. Importantly, the operando X-ray diffraction investigation reveals a reversible potassiation/depotassiation reaction mechanism of (Bi,Sb) ↔ K(Bi,Sb) ↔ K3(Bi,Sb) for the BiSb@C composite. Our findings not only propose a reasonable design of high-performance alloy-based anodes in KIBs but also promote the practical use of KIBs in large-scale energy storage.
Potassium ion batteries (PIBs) are recognized as one promising candidate for future energy storage devices due to their merits of cost‐effectiveness, high‐voltage, and high‐power operation. Many ...efforts have been devoted to the development of electrode materials and the progress has been well summarized in recent review papers. However, in addition to electrode materials, electrolytes also play a key role in determining the cell performance. Here, the research progress of electrolytes in PIBs is summarized, including organic liquid electrolytes, ionic liquid electrolytes, solid‐state electrolytes and aqueous electrolytes, and the engineering of the electrode/electrolyte interfaces is also thoroughly discussed. This Progress Report provides a comprehensive guidance on the design of electrolyte systems for development of high performance PIBs.
Electrolytes play a critical role in the electrochemical performance of emerging potassium‐ion batteries (PIBs). The research progress on electrolytes of PIBs is summarized in terms of fundamental properties, optimization of electrolyte components and engineering of electrode/electrolyte interfaces, providing a comprehensive guidance on designing more suitable electrolytes for high‐performance PIBs.
Developing active, robust, and nonprecious electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is highly crucial and ...challenging. In this work, a facile strategy is developed for scalable fabrication of dicobalt phosphide (Co2P)–cobalt nitride (CoN) core–shell nanoparticles with double active sites encapsulated in nitrogen‐doped carbon nanotubes (Co2P/CoN‐in‐NCNTs) by straight forward pyrolysis method. Both density functional theory calculation and experimental results reveal that pyrrole nitrogen coupled with Co2P is the most active one for HER, while Co–N–C active sites existing on the interfaces between CoN and N‐doped carbon shells are responsible for the ORR and OER activity in this catalyst. Furthermore, liquid‐state and all‐solid‐state Zn–air batteries are equipped. Co2P/CoN‐in‐NCNTs show high power density as high as 194.6 mW cm−2, high gravimetric energy density of 844.5 W h kg−1, very low charge–discharge polarization, and excellent reversibility of 96 h at 5 mA cm−2 in liquid system. Moreover, the Co2P/CoN‐in‐NCNTs profiles confirm excellent activity for water splitting.
Dicobalt phosphide–cobalt nitride core–shell particles act as double active centers and are encapsulated into the channel of N‐doped carbon nanotubes by an in situ one‐step self‐assembly and confined pyrolysis approach, which is demonstrated to afford trifunctional performance in catalyzing hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction for Zn–air batteries and water splitting.
Two-dimensional (2D) transition metal dichalcogenide (TMDC) monolayers, a class of ultrathin materials with a direct bandgap and high exciton binding energies, provide an ideal platform to study the ...photoluminescence (PL) of light-emitting devices. Atomically thin TMDCs usually contain various defects, which enrich the lattice structure and give rise to many intriguing properties. As the influences of defects can be either detrimental or beneficial, a comprehensive understanding of the internal mechanisms underlying defect behaviour is required for PL tailoring. Herein, recent advances in the defect influences on PL emission are summarized and discussed. Fundamental mechanisms are the focus of this review, such as radiative/nonradiative recombination kinetics and band structure modification. Both challenges and opportunities are present in the field of defect manipulation, and the exploration of mechanisms is expected to facilitate the applications of 2D TMDCs in the future.
The frequent outbreak of global infectious diseases has prompted the development of rapid and effective diagnostic tools for the early screening of potential patients in point-of-care testing ...scenarios. With advances in mobile computing power and microfluidic technology, the smartphone-based mobile health platform has drawn significant attention from researchers developing point-of-care testing devices that integrate microfluidic optical detection with artificial intelligence analysis. In this article, we summarize recent progress in these mobile health platforms, including the aspects of microfluidic chips, imaging modalities, supporting components, and the development of software algorithms. We document the application of mobile health platforms in terms of the detection objects, including molecules, viruses, cells, and parasites. Finally, we discuss the prospects for future development of mobile health platforms.
Biomagnetic monitoring includes fast and simple methods to estimate airborne heavy metals. Leaves of Osmanthus fragrans Lour and Ligustrum lucidum Ait were collected simultaneously with PM
from a ...mega-city of China during one year. Magnetic properties of leaves and metal concentrations in PM
were analyzed. Metal concentrations were estimated using leaf magnetic properties and meteorological factors as input variables in support vector machine (SVM) models. The mean concentrations of many metals were highest in winter and lowest in summer. Hazard index for potentially toxic metals was 5.77, a level considered unsafe. The combined carcinogenic risk was higher than precautionary value (10
). Ferrimagnetic minerals were dominant magnetic minerals in leaves. Principal component analysis indicated iron & steel industry and soil dust were the common sources for many metals and magnetic minerals on leaves. However, the poor simulation results obtained with multiple linear regression confirmed strong nonlinear relationships between metal concentrations and leaf magnetic properties. SVM models including leaf magnetic variables as inputs yielded better simulation results for all elements. Simulations were promising for Ti, Cd and Zn, whereas relatively poor for Ni. Our study demonstrates the feasibility of prediction of airborne heavy metals based on biomagnetic monitoring of tree leaves.
In this paper, the performance of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) was modeled using literature data. The paper attempted to combine different sources from the ...literature to find trends in the degradation mechanisms of HT-PEMFCs. The model focused on the activation and ohmic losses. The activation losses were defined as a function of both Pt agglomeration and loss of catalyst material. The simulations revealed that the loss of electrochemical active surface area (ECSA) was a major contributor to the total voltage loss. The ohmic losses were defined as a function of changes of acid doping level in time. The loss of conductivity increased significantly on a percentage basis over time, but its impact on the overall voltage degradation was fairly low. It was found that the evaporation of phosphoric acid caused the ohmic overpotential to increase, especially at temperatures above 180 °C. Therefore, higher temperatures can lead to shorter lifetimes but increase the average power output over the lifetime of the fuel cell owing to a higher performance at higher temperatures. The lifetime prognosis was also made at different operating temperatures. It was shown that while the fuel cell performance increased linearly with increasing temperature at the beginning of its life, the voltage decay rate increased exponentially with an increasing temperature. Based on an analysis of the voltage decay rate and lifetime prognosis, the operating temperature range between 160 °C and 170 °C could be said to be optimal, as there was a significant increase in performance compared to lower operating temperatures without too much penalty in terms of lifetime.
In order to analyze the ground vibration responses induced by the dynamic loads in a tunnel, this paper proposes a new simplified tunnel–soil model. Specifically, based on the basic theory of the ...thin-layer method (TLM), the basic solution of three-dimensional layered foundation soil displacement was derived in the cylindrical coordinate system. The perfectly matched layer (PML) boundary condition was applied to the TLM. Subsequently, a tunnel–soil dynamic interaction analysis model was established using the volume method (VM) in conjunction with the TLM-PML method. The displacement frequency response function of the foundation soil around the tunnel foundation was derived. Finally, a ground vibration test under an impact load in a tunnel was carried out. The test and calculated results were compared. The comparison results show that the ground vibration acceleration response values within 25 m from the load are similar. Compared with the test results, the theoretical calculation results exhibit a decreasing trend in the range of 40–80 Hz between 25 and 60 m, with the maximum reduction being approximately one order of magnitude. In addition, the experimental comparison demonstrates that the model can be used to analyze the ground vibrations caused by underground loads.
This study focuses on investigating the performance change of a high temperature proton exchange membrane fuel cell (HT-PEMFCs) stack at different operation modes. A HT-PEMFC stack consisting of 30 ...single cells was tested both at constant load (0.4 A cm−2) and dynamic load (0.05–0.4 A cm−2) conditions at a temperature of 160 ℃ and hydrogen as anode fuel. Besides, the effect of impurities on the stack was also investigated by feeding a methanol reformate mixture to the stack anode as fuel for both constant and dynamic operation. The results reveal that the stack performance was stable after 120 h of both constant and dynamic operation with hydrogen, while the stack performance decreased greatly when the stack was fed with dry reformate on the anode. Significant degradation rates of 94.4 µV h−1 for constant operation, while the degradation was 200 times higher in dynamic operation with reformate gas.
•Both constant and dynamic load effects on HT-PEMFC stack performance were studied.•Fuel impurity effect was investigated on HT-PEMFC stack.•Dynamic operation with H2 as fuel didn’t cause great stack performance loss.•Constant operation with reformates led to recoverable performance degradation.•Dynamic operation with reformates led to severe stack performance degradation.
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•TzDva-COOH and TzDva-NH2 were fabricated by a thiol-ene click reaction.•Two COFs presented high adsorption capacity and selectivity for U(VI).•Free amino and carboxyl groups ...contributed to the capture of U(VI).•DFT calculations revealed the coordination modes of U(VI) with COFs.
Uranium pollution was a key problem affecting the sustainable development of nuclear energy. Herein, a novel covalent organic frameworks (TzDva) was constructed by the irreversible imidization reaction between 2, 4, 6-tris(4-aminophenyl)-1, 3, 5-triazine (Tz) and 2, 5-divinylterephthalal-dehyde (Dva), which were further functionalized by dimercaptosuccinic acid (DMSA) and 2-aminoethanethiol (AET) for efficient elimination of uranium(VI) from wastewater. Different spectral techniques were used to characterize the microscopic morphology and structure of all the adsorbents. The experimental results showed that the carboxyl functional groups exhibited a strong affinity for uranium(VI) than that of the amino functional groups, and the maximum extraction capacities of TzDva-COOH and TzDva-NH2 were 139.5 and 88.3 mg.g−1, respectively. Selectivity experiments and simulated high salinity systems displayed that the two COFs had not only strong affinity for U(VI), but also powerful salt resistance. Meanwhile, the two COFs materials also exhibited good stability and high reusability after three adsorption–desorption cycles. Besides, spectroscopic analyses and DFT calculation demonstrated that the main adsorption mechanism involved electrostatic interactions, chelation and surface complexation. Thus, this work served as a good guideline for fabricate a novel COFs based materials to treat uranium-containing wastewater.
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