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•Proton conductive carboxylate-based MOFs were reviewed.•Aliphatic carboxylate-based and aromatic carboxylate-based MOFs were included.•Proton conductivity and conducting mechanism ...were discussed.•The future development trend of such MOFs is prospected.
As a significant type of crystalline solid proton conducting materials, metal–organic frameworks (MOFs) have been paid great attention and pursued by researchers. In this review, we will mainly summarize the proton conduction explorations of MOFs based on carboxylate ligands (including aliphatic carboxylate-based and aromatic carboxylate-based MOFs) from the aspects of synthetic strategies, stability, proton conductive properties and mechanism, application, etc. Finally, on the basis of summarization of literature and our own research on proton conduction, development prospects and challenges for such conductive materials in the future are highlighted.
The radial drift and diffusion of dust particles in protoplanetary disks affect both the opacity and temperature of such disks, as well as the location and timing of planetesimal formation. In this ...paper, we present results of numerical simulations of particle-gas dynamics in protoplanetary disks that include dust grains with various size distributions. We have considered three scenarios in terms of particle size ranges, one where the Stokes number τs = 10−1−100, one where τs = 10−4−10−1, and finally one where τs = 10−3−100. Moreover, we considered both discrete and continuous distributions in particle size. In accordance with previous works we find in our multispecies simulations that different particle sizes interact via the gas and as a result their dynamics changes compared to the single-species case. The larger species trigger the streaming instability and create turbulence that drives the diffusion of the solid materials. We measured the radial equilibrium velocity of the system and find that the radial drift velocity of the large particles is reduced in the multispecies simulations and that the small particle species move on average outwards. We also varied the steepness of the size distribution, such that the exponent of the solid number density distribution, dN∕da ∝ a−q, is either q = 3 or q = 4. Overall, we find that the steepness of the size distribution and the discrete versus continuous approach have little impact on the results. The level of diffusion and drift rates are mainly dictated by the range of particle sizes. We measured the scale height of the particles and observe that small grains are stirred up well above the sedimented midplane layer where the large particles reside. Our measured diffusion and drift parameters can be used in coagulation models for planet formation as well as to understand relative mixing of the components of primitive meteorites (matrix, chondrules and CAIs) prior to inclusion in their parent bodies.
Despite high‐energy density and low cost of the lithium–sulfur (Li–S) batteries, their commercial success is greatly impeded by their severe capacity decay during long‐term cycling caused by ...polysulfide shuttling. Herein, a new phase engineering strategy is demonstrated for making MXene/1T‐2H MoS2‐C nanohybrids for boosting the performance of Li–S batteries in terms of capacity, rate ability, and stability. It is found that the plentiful positively charged S‐vacancy defects created on MXene/1T‐2H MoS2‐C, proved by high‐resolution transmission electron microscopy and electron paramagnetic resonance, can serve as strong adsorption and activation sites for polar polysulfide intermediates, accelerate redox reactions, and prevent the dissolution of polysulfides. As a consequence, the novel MXene/1T‐2H MoS2‐C‐S cathode delivers a high initial capacity of 1194.7 mAh g−1 at 0.1 C, a high level of capacity retention of 799.3 mAh g−1 after 300 cycles at 0.5 C, and reliable operation in soft‐package batteries. The present MXene/1T‐2H MoS2‐C becomes among the best cathode materials for Li–S batteries.
Phase engineered MXene/1T‐2H MoS2‐C with plentiful S‐vacancy defects is highly effective for trapping polysulfide intermediates and accelerating redox kinetics, leading to the enhanced lithium–sulfur batteries.
Ever since the beginning of this century, many kinds of materials have been reported to demonstrate colossal permittivity (CP) or a colossal dielectric constant exceeding 103. Accordingly, such CP ...materials and their further modification and improvement to achieve enhanced CP performance for promising applications in modern electronics, sensors, energy storage, and multifunctional devices have attracted extensive attention. In this Review, a general overview of the recent advances in CP materials is provided, ranging from their various categories, physical mechanisms, and modulation methods to promising applications. First, various classes of CP materials are categorized in terms of their structures and dielectric properties. Subsequently, this Review provides an insight into the CP mechanisms in views of barrier layer capacitance, defect‐dipole cluster, and polaronic effect. Moreover, the strategies and prototypical works are introduced in some aspects, including the manipulation of CP properties by doping, percolative capacitors, and the methods employed to enhance the dielectric behaviors in CP materials with different forms. The authors then discuss a wide range of applications based on CP materials, such as modern electronics and energy storage. Finally, the challenges and opportunities for further investigation of CP materials are highlighted in the summary and future perspectives.
A variety of colossal permittivity (CP) materials and their further modification to achieve enhanced performance for promising applications in modern electronics, energy storage, and multifunctional devices have attracted extensive attention. The types of CP material, physical mechanisms, performance manipulation, and a wide range of applications are systematically reviewed. Challenges and perspectives in this field are also presented.
Monolayer VSe2, featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition‐metal dichalcogenides (2D‐TMDs). Herein, ...by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X‐ray and angle‐resolved photoemission, and X‐ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T‐phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular‐beam epitaxy. Element‐specific X‐ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long‐range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic‐scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D‐TMDs in the search for exotic low‐dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.
Monolayer VSe2 represents a unique system for exploring the interplay between charge density wave and magnetism phenomena. Evidence of spin frustration is obtained in monolayer VSe2, which is significant toward the search for exotic low‐dimensional quantum phases and further theoretical and experimental studies of van der Waals monolayer magnets.
The authors review the recent advances in the development of high‐strength titanium alloys. First, they summarize conventional strengthening approaches and their mechanisms, thecorresponding ...microstructures, and the optimized mechanical properties. Subsequently, various strengthening strategies for high‐strength titanium alloys are discussed. Finally, examples of the successful development of high‐strength titanium alloys based on amorphous crystallization via solid and semi‐solid sintering are presented. The review of the interrelation between the microstructure, the strengthening, and the properties may provide significant insight into achieving novel high‐strength titanium alloys.
Development of bimodal/multimodal microstructure has attracted extensive attention in the balance of high strength and ductility of titanium alloys. This review covers the development strategies of ultrahigh strength titanium alloys consisting of nanoscale and microscale grains. Specially, a novel semi‐solid sintering technique for preparing bimodal structured titanium alloys composed of nanostructured eutectic matrix and micron‐sized precipitated phases has been proposed.
The construction of a garden image classification model is done by combining spatial information technology and analyzing the process of hyperspectral classification of garden images is the main ...focus of this paper. The linear transformation of the image is performed by principal component analysis to achieve the effect of reducing image dimension. The SVM classifier is used to classify the garden images, and the hyperplane is found in the sample space to distinguish between positive and negative cases. Using a simple linear iterative algorithm, the image superpixels are segmented, and the information contained in them is fused with the features of the hyperspectral image. The positioning of the hyperpixel block impacts the calculation of the mean hyperspectral feature value for each hyperpixel region. The results show that a well-rounded designer needs to achieve 70% aesthetics and 80% rationality to present modern garden design.
The synergistic efficacy of phototherapy and cancer immunotherapy is severely restricted by both the inherent photobleaching and aggregation‐caused quench (ACQ) defects of photosensitizers and the ...intrinsic antioxidant tumor microenvironment (TME), such as hypoxia and overexpressed glutathione (GSH). To address these issues, a novel porphyrin‐based staggered stacking covalent organic framework (COF), COF‐618‐Cu, is rationally designed as a reactive oxygen species (ROS) amplifier, owing to its excellent catalase‐like activity, COF‐618‐Cu is capable of consuming endogenous hydrogen peroxide to produce sufficient oxygen to alleviate the tumor hypoxia phenomena. Moreover the overexpressed intracellular GSH is also depleted to decrease the scavenging of ROS, due to the glutathione peroxidase mimic activity of COF‐618‐Cu. Mechanistic studies reveal that the unique staggered stacking mode between COF‐618‐Cu interlayers can effectively relieve both the photobleaching and ACQ effects that are inaccessible to commonly eclipsed COFs. These, combined with their excellent photothermal therapy performance, make COF‐618‐Cu favorable for inducing robust immunogenic cell death and remodeling TME to boost antitumor immunity.
A novel staggered stacking covalent organic framework (COF)‐based photosensitizer, COF‐618‐Cu, is reported, which can simultaneously alleviate photobleaching and aggregation‐induced quench effects to achieve desirable phototherapy performance and further elicit robust immunogenic cell death to trigger a durable antitumor immune response for boosting cancer immunotherapy.
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