The shuttling of soluble lithium polysulfides between the electrodes leads to serious capacity fading and excess use of electrolyte, which severely bottlenecks practical use of Li‐S batteries. Here, ...selective catalysis is proposed as a fundamental remedy for the consecutive solid‐liquid‐solid sulfur redox reactions. The proof‐of‐concept Indium (In)‐based catalyst targetedly decelerates the solid‐liquid conversion, dissolution of elemental sulfur to polysulfides, while accelerates the liquid‐solid conversion, deposition of polysulfides into insoluble Li2S, which basically reduces accumulation of polysulfides in electrolyte, finally inhibiting the shuttle effect. The selective catalysis is revealed, experimentally and theoretically, by changes of activation energies and kinetic currents, modified reaction pathway together with the probed dynamically changing catalyst (LiInS2 catalyst), and gradual deactivation of the In‐based catalyst. The In‐based battery works steadily over 1000 cycles at 4.0 C and yields an initial areal capacity up to 9.4 mAh cm−2 with a sulfur loading of ≈9.0 mg cm−2.
Selective catalysis is proposed as a fundamental remedy for consecutive solid–liquid–solid sulfur redox reactions. This proof‐of‐concept In‐based catalyst targetedly decelerates the solid–liquid conversion, dissolution of elemental sulfur to polysulfides, while accelerating the liquid–solid conversion, deposition of polysulfides into insoluble Li2S, which basically reduces accumulation of polysulfides in the electrolyte, finally inhibiting the shuttle effect in Li–S batteries.
2D lamellar materials can offer high surface area and abundant reactive sites, thus showing an appealing prospect in photocatalytic hydrogen evolution. However, it is still difficult to build ...cost‐efficient photocatalytic hydrogen evolution systems based on 2D materials. Herein, an in situ growth method is employed to build 2D/2D heterojunctions, with which 2D Ni‐based metal–organic layers (Ni‐MOLs) are closely grown on 2D porous CdS (P‐CdS) nanosheets, affording traditional P‐CdS/Ni‐MOL heterojunction materials. Impressively, the optimized P‐CdS/Ni‐MOL catalyst exhibits superior photocatalytic hydrogen evolution performance, with an H2 yield of 29.81 mmol g−1 h−1. This value is 7 and 2981 times higher than that of P‐CdS and Ni‐MOLs, respectively, and comparable to those of reported state of the art catalysts. Photocatalytic mechanism studies reveal that the enhanced photocatalytic performance can be attributed to the 2D/2D intimate interface between P‐CdS and Ni‐MOLs, which facilitates the fast charge carriers’ separation and transfer. This work provides a strategy to develop 2D MOL‐based photocatalysts for sustainable energy conversion.
The ultrathin structure and large specific surface area of the P‐CdS/Ni‐MOL composites are of great benefit for exposing more active sites and expanding contact surface area. In such a way, the recombination of photoinduced electrons/holes pairs can be efficiently inhibited. The synergistic effect of the intimate contact between P‐CdS and Ni‐MOLs can significantly enhance the photocatalytic H2 evolution performances.
The Assembly of MXenes from 2D to 3D Wu, Zhitan; Shang, Tongxin; Deng, Yaqian ...
Advanced science,
04/2020, Volume:
7, Issue:
7
Journal Article
Peer reviewed
Open access
Since their discovery in 2011, transition metal carbides or nitrides (MXenes) have attracted a wide range of attention due to their unique properties and promise for use in a variety of applications. ...However, the low accessible surface area and poor processability of MXene nanosheets caused by their restacking have severely hindered their practical use, and this is expected to be solved by integrating them into macroscopic assemblies. Here, recent progress in the construction of MXene assemblies from 2D to 3D at the macro and/or microlevel is summarized. The mechanisms of their assembly are also discussed to better understand the relationship between performance and assembled structure. The possible uses of MXene assemblies in energy conversion and storage, electromagnetic interference shielding and absorption, and other applications are summarized.
The MXene assemblies are promising for broadening the applications of MXenes and promoting their realization in practice. Herein, the MXene assemblies from 2D to 3D at macro and/or microlevels are reviewed. The corresponding assembly mechanisms and applications are also summarized to better deepen the cognition of relationships between assembled structures and specific applications.
Assembly of 2D MXene sheets into a 3D macroscopic architecture is highly desirable to overcome the severe restacking problem of 2D MXene sheets and develop MXene‐based functional materials. However, ...unlike graphene, 3D MXene macroassembly directly from the individual 2D sheets is hard to achieve for the intrinsic property of MXene. Here a new gelation method is reported to prepare a 3D structured hydrogel from 2D MXene sheets that is assisted by graphene oxide and a suitable reductant. As a supercapacitor electrode, the hydrogel delivers a superb capacitance up to 370 F g−1 at 5 A g−1, and more promisingly, demonstrates an exceptionally high rate performance with the capacitance of 165 F g−1 even at 1000 A g−1. Moreover, using controllable drying processes, MXene hydrogels are transformed into different monoliths with structures ranging from a loosely organized porous aerogel to a dense solid. As a result, a 3D porous MXene aerogel shows excellent adsorption capacity to simultaneously remove various classes of organic liquids and heavy metal ions while the dense solid has excellent mechanical performance with a high Young's modulus and hardness.
A new MXene gelation method is demonstrated by assembling MXene flakes into a 3D hydrogel in the presence of graphene oxide and ethylene diamine. The resulting hydrogel shows an ultrahigh capacitance and an exceptionally high rate performance for supercapacitors and is ready to produce a MXene porous aerogel and dense solid with great promise in pollutant removal and compact energy storage.
We describe validated protocols for generating high-quality, full-length severe acute respiratory syndrome coronavirus 2 genomes from primary samples. One protocol uses multiplex reverse ...transcription PCR, followed by MinION or MiSeq sequencing; the other uses singleplex, nested reverse transcription PCR and Sanger sequencing. These protocols enable sensitive virus sequencing in different laboratory environments.
Alzheimer's disease (AD) is an age-related neurodegenerative disease that is mediated by multiple signaling pathways. In recent years, the components of
(PF) have demonstrated some anti-Alzheimer ...effects both in vitro and in vivo. To further reveal the active compounds of PF and their mechanisms regulating key targets of AD, in this study, we identified four prenylated compounds from the 70% ethanolic aqueous extract of PF, namely bavachin, bavachinin, bavachalcone, and isobavachalcone. Multi-target bioactivity analysis showed that these compounds could differentially inhibit neuroinflammation, oxidative damage, and key AD-related protein targets, such as amyloid β-peptide 42, β-secretase, glycogen synthase kinase 3β, and acetylcholinesterase. These compounds may generate beneficial effects in AD prevention and treatment.
Abstract
Magnesium alloys with high strength and excellent corrosion resistance are always sought-after in light-weighting structural components for automotive and aerospace applications. However, ...for most magnesium alloys that have a high specific strength, they usually have an inferior corrosion resistance and vice versa. In this work, we successfully develop a Mg-11Y-1Al (wt. %) alloy through conventional casting, solution treatment followed by extrusion. The overall properties of this alloy feature with a corrosion rate lower than 0.2 mm y
−1
, high yield strength of 350 MPa and moderate tensile elongation of 8%, the combination of which shows competitive advantage over other comparative magnesium alloys in the literature. It is found that a thin and dense protective film of Y
2
O
3
/Y(OH)
3
can be fast developed with the aid of Al
2
O
3
/Al(OH)
3
deposition to isolate this alloy from further attack of corrosion medium. Meanwhile, the refined grains, weak texture and activation of non-basal slip systems co-contribute to the high strength and good ductility. Our findings are expected to inspire the design of next-generation high performance magnesium alloys.
Context
Multifocality and bilaterality are common in patients with papillary thyroid microcarcinoma (PTMC). However, their clinical behaviours and prognostic implications remain controversial.
...Objective
To investigate the relationship between multifocality and classically aggressive characteristics and outcomes in patients with PTMC.
Methods
Clinical data of 3005 patients with PTMC were retrospectively reviewed at a tertiary medical centre. The role of unilateral and bilateral multifocality in aggressive characteristics and clinical outcomes of PTMC was evaluated using propensity score matching (PSM).
Results
A total of 573 patients had bilateral multifocal disease (B‐MFD), 272 had unilateral multifocal disease (U‐MFD), and 2160 had unifocal disease (UFD). Univariate analysis showed that patients in the multifocal disease (MFD) groups showed significantly different characteristics compared to patients in the UFD group in terms of age, chronic lymphocytic thyroiditis (CLT), follicular variant PTMC, tumour diameter, aggressive growth, including extrathyroidal extension (ETE), central lymph node metastasis (CLNM) and lateral lymph node metastasis (LLNM), and TNM stage, and underwent radioactive iodine (RAI) therapy. Further stratified analysis revealed that patients in the B‐MFD group reflected the differences between the MFD and UFD groups. However, those in the U‐MFD group showed slight differences only in sex, CLT and cell subtypes, compared to the UFD group. In addition, PSM indicated differences in ETE, CLNM and LLNM between the B‐MFD and UFD groups (p < .001), while only ETE differed between the U‐MFD and UFD groups (p < .001). After a median follow‐up period of 60 months, no difference was observed in recurrence‐free survival between the UFD and B‐MFD (p = .294) or U‐MFD (p = .603) groups using PSM.
Conclusion
This propensity score matching analysis provides strong evidence that bilateral multifocality, rather than unilateral multifocality, should be considered as an aggressive marker at presentation, and neither is an independent prognostic factor for clinical outcome in PTMC.
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