Insight into demand-driven preparation of single-atomic mediators for lithium–sulfur batteries

Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to the severe shuttle effect,sluggish redox kinetics and lithium dendritic growth.Single-atomic mediators as promising candidates exhibit impressive performance in addressing these intractable issues.Related research often utilizes a trial-and-error approach,proposing solutions to fabricate single-atomic materials with diversified features.However,comprehensive review articles especially targeting demand-driven preparation are still in a nascent stage.Inspired by these considerations,this review summarizes the design of single-atomic mediators based on the application case-studies in LiS batteries and other metal-sulfur systems.Emerging preparation routes represented by chemical vapor deposition technology are introduced in a demand-oriented classification.Finally,future research directions are proposed to foster the advancement of single-atomic mediators in Li-S realm.

Tuning dual-atom mediator toward high-rate bidirectional polysulfide conversion in Li-S batteries

An emerging practice in the realm of Li-S batteries lies in the employment of single-atom catalysts(SACs)as effective mediators to promote polysulfide conversion,but monometallic SACs affording isolated geometric dispersion and sole electronic configuration limit the catalytic benefits and curtail the cell performance.Here,we propose a class of dual-atom catalytic moieties comprising hetero-or homo-atomic pairs anchored on N-doped graphene(NG)to unlock the liquid–solid redox puzzle of sulfur,readily realizing Li-S full cell under high-rate-charging conditions.As for Fe-Ni-NG,in-depth experimental and theoretical analysis reveal that the hetero-atomic orbital coupling leads to altered energy levels,unique electronic structures,and varied Fe oxidation states in comparison with homo-atomic structures(FeFe-NG or Ni-Ni-NG).This would weaken the bonding energy of polysulfide intermediates and thus enable facile electrochemical kinetics to gain rapid liquid-solid Li_(2)S_(4)?Li_(2)S conversion.Encouragingly,a Li-S battery based on the S@Fe-Ni-NG cathode demonstrates unprecedented fast-charging capability,documenting impressive rate performance(542.7 mA h g^(-1)at 10.0 C)and favorable cyclic stability(a capacity decay of 0.016%per cycle over 3000 cycles at 10.0 C).This finding offers insights to the rational design and application of dual-atom mediators for Li-S batteries.

Specific Relationship between the Surface Air Temperature and the Area of the Terra Nova Bay Polynya,Antarctica

Antarctic polynyas play an important role in regional atmosphere?ice?ocean interactions and are considered to help generate the global deep ocean conveyer belt.Polynyas therefore have a potential impact on the Earth’s climate in terms of the production of sea ice and high-salinity shelf water.In this study,we investigated the relationship between the area of the Terra Nova Bay polynya and the air temperature as well as the eastward and northward wind based on the ERA5 and ERAInterim reanalysis datasets and observations from automatic weather stations during the polar night.We examined the correlation between each factor and the polynya area under different temperature conditions.Previous studies have focused more on the effect of winds on the polynya,but the relationship between air temperature and the polynya area has not been fully investigated.Our study shows,eliminating the influence of winds,lower air temperature has a stronger positive correlation with the polynya area.The results show that the relationship between the polynya area and air temperature is more likely to be interactively influenced.As temperature drops,the relationship of the polynya area with air temperature becomes closer with increasing correlation coefficients.In the low temperature conditions,the correlation coefficients of the polynya area with air temperature are above 0.5,larger than that with the wind speed.

Frame Construction and Task Analysis of Smart Energy in the Construction of Smart City

Smart energy is the foundation and important component of smart cities, and it is the source of energy that guarantees the efficient and reliable operation of each subsystem of the city. Based on the practical experience in the exploration of the construction of smart energy at home and abroad, and the goal of achieving “three transformations and one center”, the basic principles of the frame construction as well as display construction and physical construction of smart energy have been proposed. Four main tasks of the construction of smart energy have been discussed: infrastructure, energy supply, energy consumption, and management services.

Assessment of Snow Depth over Arctic Sea Ice in CMIP6 Models Using Satellite Data

Snow depth over sea ice is an essential variable for understanding the Arctic energy budget.In this study,we evaluate snow depth over Arctic sea ice during 1993-2014 simulated by 31 models from phase 6 of the Coupled Model Intercomparison Project(CMIP6)against recent satellite retrievals.The CMIP6 models capture some aspects of the observed snow depth climatology and variability.The observed variability lies in the middle of the models’simulations.All the models show negative trends of snow depth during 1993-2014.However,substantial spatiotemporal discrepancies are identified.Compared to the observation,most models have late seasonal maximum snow depth(by two months),remarkably thinner snow for the seasonal minimum,an incorrect transition from the growth to decay period,and a greatly underestimated interannual variability and thinning trend of snow depth over areas with frequent occurrence of multi-year sea ice.Most models are unable to reproduce the observed snow depth gradient from the Canadian Arctic to the outer areas and the largest thinning rate in the central Arctic.Future projections suggest that snow depth in the Arctic will continue to decrease from 2015 to 2099.Under the SSP5-8.5 scenario,the Arctic will be almost snow-free during the summer and fall and the accumulation of snow starts from January.Further investigation into the possible causes of the issues for the simulated snow depth by some models based on the same family of models suggests that resolution,the inclusion of a hightop atmospheric model,and biogeochemistry processes are important factors for snow depth simulation.

Uniqueness of Lekima compared to tropical cyclones landed in the east coast of China during 1979–2019

Tropical cyclone (TC) causes huge damage to lives and properties due to strong winds,storm surge,heavy rainfall and flooding(Peduzzi et al.,2012;Zhang et al.,2009).Climate model simulations suggested that the frequency of TCs might increase during the 21st century,especially over the western North Pacific (Emanuel,2013).Climate changes tend to double the economic damages caused by natural disaster,i.e.,strong TCs.East Asia hit by TCs may suffer great damages in the future (Mendelsohn et al.,2012).

Core-shell structured Ru-Ni@SiO_2: Active for partial oxidation of methane with tunable H_2/CO ratio

This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature（700℃）.Compared to the impregnation method,the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles.Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction,accounting for better catalyst performance.Enriched surface Ru species hinders surface carbon deposition,but also declines overall activity and H2/CO ratio,meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions.Over the current（m%Ru-Ni）@Si O2catalyst,the formation of fibrous carbon species is suppressed,which accounts for good stability of catalyst within a TOS of 10 h.

Effect of dose rate on the characteristics of dislocation loops in palladium:In-situ TEM analysis during 30 keV H_(2)^(+)irradiation

Ion irradiation is usually used to simulate neutron irradiation to accelerate the evaluation of the irradia-tion behavior of reactor materials.However,the validity of using a high damage rate of ion irradiation to simulate a low damage rate of neutron irradiation has always been a controversial topic.Here,the effect of two dose rates(2.94×10^(-6) and 7.35×10^(-5) dpa s^(-1))on the characteristics and evolution of dislo-cation loops in palladium was studied in situ during 30 keV H2+irradiation using transmission electron microscopy.The dose rate obviously affected the nucleation rate and growth rate of dislocation loops,the types(Frank loops or perfect loops)of dislocation loops,and the irradiation hardening and total damage obtained from the product of average loop size and loop density.At the same irradiation dose,a high dose rate would lead to high loop density,small average loop size,low loop growth rate,and low irra-diation hardening and damage induced by loops in pure Pd.Meanwhile,it was found for the first time that a high dose rate was beneficial to the generation of perfect dislocation loops.The effect of dose rate was attributed to the different dynamic equilibrium results between the effective generation rate of point defects and their absorption rate by existing sinks.The present results show that the effect of dose rate should be considered when using ion irradiation to simulate neutron irradiation to evaluate the irradiation damage to materials.

Decorating Vertically Oriented Graphene Arrays with Co-Doped NiTe_(2)Toward Al-Current-Collector-Free Li-S Batteries

Lithium-sulfur(Li-S)batteries are broadly regarded as one of the most promising energy storage systems owing to their high-energy and low-cost features.Nevertheless,their practical implementation is plagued by the notorious polysulfide shuttling and sluggish reaction kinetics.Transition metal telluride has emerged as a promising electrocatalyst to expedite sulfur redox kinetics,even though its controllable and precise fabrication remains quite elusive.Herein,we propose the employment of a chemical vapor deposition approach to achieve in situ growth of Co-doped NiTe_(2)(Co-NiTe_(2))on vertically oriented graphene coated carbon cloth(VG/CC)substrate,in the pursuit of high-performance sulfur host material(Co-NiTe_(2)@VG/CC)in Li-S realms.Electrokinetic analysis and operando Raman spectroscopy characterization reveal the effective regulation capability of Co-NiTe_(2)@VG/CC with respect to polysulfide capture/conversion and Li2S decomposition.As a result,the Al-currentcollector-free Co-NiTe_(2)@VG/CC-based cathodes with typical sulfur loading exhibit outstanding cycling stability(93.8% capacity retention over 100 cycles at 0.5 C).Moreover,an areal capacity of 4.27 mAh cm^(-2) at 0.2 C can be harvested even at an elevated sulfur loading of 7.2 mg cm^(-2).

Towards reliable Arctic sea ice prediction using multivariate data assimilation

Rapid declines in Arctic sea ice have captured attention and pose significant challenges to a variety of stakeholders. There is a rising demand for Arctic sea ice prediction at daily to seasonal time scales, which is partly a sea ice initial condition problem. Thus, a multivariate data assimilation that integrates sea ice observations to generate realistic and skillful model initialization is needed to improve predictive skill of Arctic sea ice. Sea ice data assimilation is a relatively new research area. In this review paper, we focus on two challenges for implementing multivariate data assimilation systems for sea ice forecast. First, to address the challenge of limited spatiotemporal coverage and large uncertainties of observations, we discuss sea ice parameters derived from satellite remote sensing that(1) have been utilized for improved model initialization, including concentration, thickness and drift, and(2) are currently under development with the potential for enhancing the predictability of Arctic sea ice, including melt ponds and sea ice leads. Second, to strive to generate the ‘‘best" estimate of sea ice initial conditions by combining model simulations/forecasts and observations, we review capabilities and limitations of different data assimilation techniques that have been developed and used to assimilate observed sea ice parameters in dynamical models.

Iceberg calving from the Antarctic Nansen Ice Shelf in April 2016 and its local impact

Owing to global warming,frequent ice shelf disintegration and rapid acceleration of inland ice flow have occurred in recent decades,which impacts the Antarctic mass balance and the global sea level[1].These events are closely linked to atmospheric and oceanic processes.The prolonged melt season and larger extent of melt ponds on the ice shelf surface[2],as well as enhanced basal melting caused by warmer sea water[3],will induce crevasses that

In-situ TEM observation of the evolution of helium bubbles & dislocation loops and their interaction in Pd during He^(+) irradiation

The microstructural evolution of purity Pd under 30 keV He^(+)irradiation at 573 K was investigated by in-situ transmission electron microscopy.The nucleation,growth,merging,annihilation,size change,number density variation,and types of dislocation loops were analyzed under the influence of irradiation fluence and sample thickness.Both perfect dislocation loops with b=1/2<110>and faulted dislocation loops with b=1/3<111>were formed.However,at low irradiation fluence,most of the loops were 1/3<111>loops.The thickness of TEM foil obviously affected the ratio of 1/3<111>loop variants,the size and number density of dislocation loops,and the characteristics of bubble-loop complexes.With the increase of irradiation fluence,the size of dislocation loops increased,but loop volume number density remained almost constant until dislocation loops merged and evolved into dislocation network.There was an obvious interaction between dislocation loops and bubbles,indicating that 1/3<111>loop was first formed at the initial stage of irradiation,and when the loop grew to a certain size,obvious helium bubbles appeared inside its region.

N-doped MoS_(2) via assembly transfer on an elastomeric substrate for high-photoresponsivity,air-stable and stretchable photodetector

As a direct-bandgap semiconductor,single-layer MoS_(2) has gained great attention in optoelectronics,especially wearable photodetectors.However,MoS_(2) exhibits poor photoresponsivity on a stretchable substrate due to intrinsic low carrier density and a large number of scattering centers on polymer substrates.Few air-stable yet strong dopants on MoS_(2) has been reported.In addition,the roughness,hydrophobicity and susceptibility to organic solvents of polymer surface are critical roadblocks in the development of stretchable high-performance MoS_(2) photodetectors.Here,we realize a stretchable and stable photodetector with high photoresponsivity by combining n-type dopant((4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine,N-DMBI)with MoS_(2) and assembly transfer technique.It is found electron tends to transfer from N-DMBI to MoS_(2) and the effect is maintained after the integrable photodetector transferred directly by elastic substrate styrene-ethylene-butylene-styrene(SEBS),even after being exposed to the air for 20 days,which benifits greatly from the encapsulation of SEBS.The increased carrier density greatly promotes carrier injection efficiency and photogenerated electron–hole separation efficiency at the metal–semiconductor interface,thus offering a significantly improved photoresponsivity in MoS_(2) photodetectors.Moreover,such photodetector shows great durability to stretch,which can remain functional after stretched 100 cycles within its stretch limit.Our strategy opens a new avenue to fabricate high-photoresponsivity stretchable electronics or optoelectronics of two-dimensional(2D)materials.

Co-delivery of luteolin and TGF-β1 plasmids with ROS-responsive virus-inspired nanoparticles for microenvironment regulation and chemo-gene therapy of intervertebral disc degeneration

Intervertebral disc degeneration(IDD)is closely related to inflammation and imbalance of synthesis/catabolism of extracellular matrix(ECM)in intervertebral disc(IVD).Considering this,luteolin(LUT),a kind of natural flavonoid with good anti-inflammatory effect and TGF-β1(a gene that promotes the regeneration of ECM)plasmid was co-loaded and co-delivered to nucleus pulposus cells(NPCs).Reactive oxygen species(ROS)responsive cationic copolymer,poly(β-amino ester)-poly(ε-caprolactone)(PBC),with high plasmid DNA(pDNA)compression affinity was synthesized.It can self-assemble into nano-sized polyplexes(pDNA@PBC)with virus-inspired structure and function through which it can transfect pDNA into NPCs with very high efficiency and negligible cytotoxicity.LUT was encapsulated in the hydrophobic core of pDNA@PBC.The co-delivery system,LUT-pTGFβ1@PBC,could enhance the cellular uptake of NPCs and manifest excellent sustained drug release in IVD.Real time quantitative polymerase chain reaction(RT-qPCR)and Western blot experiments reveal that the co-delivery system could inhibit inflammation in NPCs and restore the balance of anabolism and catabolism in vitro by activating TGF/SMAD3 and inhibiting NFkB/p65.Moreover,LUT-pTGF-β1@PBC retards IDD in vivo as detected by radiological and histological methods with good biosafety in rats.LUT-pTGF-β1@PBC may be a promising option for the treatment of IDD.

In-situ TEM investigation of dislocation loop reaction and irradiation hardening in H_(2)^(+)-He^(+) dual-beam irradiated Mo

Through in-situ TEM observation during 30 keV H_(2)^(+)-He^(+) dual-beam irradiation at 723 K,the reaction and transformation of dislocation loops in pure Mo were investigated,especially for<100>loops.Irradiation could directly cause the formation of 1/2<111>loops and<100>loops,but 1/2<111>loops were dominant.In-situ observation confirmed the formation mechanism of<100>loops,including direct irradiation induced mechanism,1/2<111>loop direct conversion mechanism,and reaction mechanism of two 1/2<111>loops.Meanwhile,the reaction of two 1/2<111>loops to produce<100>loop should not require the strict size similarity condition.The reaction between 1/2<111>loops could also produce 1/2<111>loop,which was essentially a process in which one loop absorbed another one.The yield strength increment caused by irradiation-induced loops was analyzed,and its saturation value reached0.48 GPa at 0.06 dpa.Compared with single He+irradiation,the number density and average diameter of loops increased significantly and more serious damage was caused under the synergistic effect of hydrogen and helium.The mechanism based on in-situ experimental observation was discussed in depth.

Surface roughening of Nafion membranes using different route planning for IPMCs

In this paper,three different roughening route planning methods(free coarsening,vertical coarsening,circling coarsening)were designed to pre-treat the basement membrane.The platinum IPMC was prepared by electroless plating to observe their surface morphology and test their performances such as output displacement and blocking force.The results show that the platinum electrode of the vertical coarsening route planning of IPMC is distributed in the shape of fish scales and is the most compact and regular on the surface electrode.The thickness of the platinum electrode layer is about 13μm,the maximum output displacement is 54.89 mm,the blocking force of 15.46 mN,and the maximum strain energy density of the IPMC of 2.44 KJ/m^(3).Vertical coarsening route planning can significantly improve the electrodynamic properties of IPMC,and it is recommended that the surface roughening of IPMC be utilized in the research and application of IPMC.It lays a certain experimental foundation for the performance improvement and innovation research and development of IPMC in the subsequent stage.

Effect of Dislocation Mechanism on Elastoplastic Behavior of Crystals with Heterogeneous Dislocation Distribution

Gradient structures have excellent mechanical properties,such as synergetic strength and ductility.It is desirable to reveal the connection between the gradient structure and mechanical properties.However,few studies have been conducted for materials with heterogeneous dislocation distribution.In the present study,we use the discrete dislocation dynamics(DDD)method to investigate the effect of dislocation density gradient on the elastoplastic behavior of single crystals controlled by source activation.In contrast to the intuitive expectation that gradient structure affects the mechanical properties,the DDD simulations show that the elastic moduli and yield stresses of three gradient samples(i.e.,no gradient,low gradient,and high gradient)are almost identical.Different from the progressive elastic-plastic transition in the samples controlled by Taylor hardening(i.e.,the mutual interaction of dislocation segments),the flow stresses of source activation ones enter into a stage of nearly ideal plasticity(serrated flow)immediately after yielding.The microstructure evolution demonstrates that the mean dislocation spacing is relatively large.Thus,there are only a few or even one dislocation source activated during the plastic flow.The intermittent operation of sources leads to intensive fluctuation of stress and dislocation density,as well as a stair-like evolution of plastic strain.The present work reveals that the effect of dislocation density gradient on the mechanical response of crystals depends on the underlying dislocation mechanisms controlling the plastic deformation of materials.