Design Principles and Mechanistic Understandings of Non-Noble-Metal Bifunctional Electrocatalysts for Zinc-Air Batteries

Zinc-air batteries(ZABs)are promising energy storage systems because of high theoretical energy density,safety,low cost,and abundance of zinc.However,the slow multi-step reaction of oxygen and heavy reliance on noble-metal catalysts hinder the practical applications of ZABs.Therefore,feasible and advanced non-noble-metal elec-trocatalysts for air cathodes need to be identified to promote the oxygen catalytic reaction.In this review,we initially introduced the advancement of ZABs in the past two decades and provided an overview of key developments in this field.Then,we discussed the work-ing mechanism and the design of bifunctional electrocatalysts from the perspective of morphology design,crystal structure tuning,interface strategy,and atomic engineering.We also included theoretical studies,machine learning,and advanced characterization technologies to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions.Finally,we discussed the challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for ZABs.

Enhanced cycle performance of Li/S battery with the reduced graphene oxide/activated carbon functional interlayer

The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional(3D) reduced graphene oxide/activated carbon(RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 m Ah/g and a reversible capacity of 655 m Ah/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.

Single‐atomic Co‐B_(2)N_(2)sites anchored on carbon nanotube arrays promote lithium polysulfide conversion in lithium-sulfur batteries

Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.

Integrated host configuration of flexibly fibrous skeleton towards efficient polysulfide conversion and dendrite-free behavior in stable lithium-sulfur pouch cells

The commercialization of lithium-sulfur(Li-S) batteries is obstructed by the sluggish sulfur electrochemical reaction,severe polysulfide shuttling effect,and damaging dendritic lithium growth.Herein,a threedimensional(3D) conductive carbon nanofibers skeleton-based bifunctional electrode host material is fabricated,which consists of a two-dimensional(2D) ultra-thin NiSe_(2)-CoSe_(2)heterostructured nanosheet built on one-dimensional(1D) carbon nanofibers(NiSe_(2)-CoSe_(2)@CNF).When serving as cathodic host,the heterostructured NiSe_(2)-CoSe_(2)@CNF offers a synergistic function of polysulfide confinement and catalysis conversion.The S/NiSe_(2)-CoSe_(2)@CNF cathode shows outstanding cycling stability of 0.03% capacity decay rate per cycle over 500 cycles at 1 C.As anodic host,the NiSe_(2)-CoSe_(2)@CNF with high-flux Li+diffusion property and good lithiophilic capability realizes dendrite-free Li plating/stripping behavior.Benefiting from these synergistically merits,the Li-S full cell with S/NiSe_(2)-CoSe_(2)@CNFILi/NiSe_(2)-CoSe_(2)@CNF electrodes exhibits excellent electrochemical performance including a high specific capacity of1021 mA h g^(-1)over 100 cycles at 0.2 C and reversible areal capacity of 3.05 mA h cm^(-2)under a high sulfur loading of 4.33 mg cm^(-2)at 0.1 C.The pouch cell also delivers ultra-stable Li/S electrochemistry.This study demonstrates a rational and universal electrode construction strategy for developing practical and high-energy Li-S batteries.

Constructing Abnormal Step-Scheme Nano-Heterointerfaces as Sulfur Electrocatalysts with Desirable Electron Confinement for Practical Li-S Battery

Heterostructured sulfur electrocatalysts have long been heralded as an effective approach to settle the issues of the shuttle effect and sluggish reaction kinetics of lithium polysulfides(LiPSs)in lithium-sulfur(Li-S)batteries.However,the limited active sites on the interface of the heterostructure offer unsatisfactory LiPSs conversion capability,rendering sluggish reaction kinetics.Herein,we have designed abnormal step-scheme nano-heterointerfaces,containing P-N,N-semimetal,and P-semimetal heterostructures as sulfur electrocatalysts to regulate the LiPSs catalytic conversion behavior,which demonstrates efficient catalytic activity and robust structural stability.The excellent electron-confinement contributed by the step-scheme barrier endows the electron gathering at the nano-heterointerfaces,conferring high selectivity and durability of electrocatalyst for an accelerated sulfur reduction reaction.The unique robust structure design further bestows the sulfur composite with favored ion/mass transportation within the electrode.Attributed to these structural features,the Li-S cell delivers excellent performance under high areal capacity over 7 mAh cm^(−2) and lean electrolyte/sulfur ratio below 2.5μL mg^(−1),decent rate capability up to 8 C,remarkable cyclic stability over 500 cycles,and satisfactory energy density of 386.3 Wh kg^(−1) in a 7.5 Ah pouch cell.This nano-heterointerface structure design strategy endows a sulfur cathode with superior LiPSs catalytic activity,opening new insights into high-performance Li-S batteries.

Assessing phenological change in China from 1982 to 2006 using AVHRR imagery

Long-term trends in vegetation phenology indicate ecosystem change due to the combined impacts of human activities and climate. In this study we used 1982 to 2006 Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index （AVHRR NDVI） imagery across China and the TIMESAT program to quantify annual vegetation production and its changing trend. Results showed great spatial variability in vegetation growth and its temporal trend across the country during the 25-year study period. Significant decreases in vegetation production were detected in the grasslands of Inner Mongolia, and in industrializing regions in southern China, including the Pearl River Delta, the Yangtze River Delta, and areas along the Yangtze River. Significant increases in vegetation production were found in Xinjiang, Central China, and North-east China. Validation of the NDVI trends and vegetated area changes were conducted using Landsat imagery and the results were consistent with the analysis from AVHRR data. We also found that although the causes of the vegetation change vary locally, the spatial pattern of the vegetation change and the areas of greatest impact from national policies launched in the 1970s, such as the opening of economic zones and the ＇Three-North Shelter Forest Programme＇, are similar, which indicates an impact of national policies on ecosystem change and that such impacts can be detected using the method described in this paper.

Exploring Seasonal and Circadian Rhythms in Structural Traits of Field Maize from LiDAR Time Series

Plant growth rhythm in structural traits is important for better understanding plant response to the ever-changing environment.Terrestrial laser scanning(TLS)is a well-suited tool to study structural rhythm under field conditions.Recent studies have used TLS to describe the structural rhythm of trees,but no consistent patterns have been drawn.Meanwhile,whether TLS can capture structural rhythm in crops is unclear.Here,we aim to explore the seasonal and circadian rhythms in maize structural traits at both the plant and leaf levels from time-series TLS.The seasonal rhythm was studied using TLS data collected at four key growth periods,including jointing,bell-mouthed,heading,and maturity periods.Circadian rhythms were explored by using TLS data acquired around every 2 hours in a whole day under standard and cold stress conditions.Results showed that TLS can quantify the seasonal and circadian rhythm in structural traits at both plant and leaf levels.(1)Leaf inclination angle decreased significantly between the jointing stage and bell-mouthed stage.Leaf azimuth was stable after the jointing stage.(2)Some individual-level structural rhythms(e.g.,azimuth and projected leaf area/PLA)were consistent with leaf-level structural rhythms.(3)The circadian rhythms of some traits(e.g.,PLA)were not consistent under standard and cold stress conditions.(4)Environmental factors showed better correlations with leaf traits under cold stress than standard conditions.Temperature was the most important factor that significantly correlated with all leaf traits except leaf azimuth.This study highlights the potential of time-series TLS in studying outdoor agricultural chronobiology.

Nickel embedded porous macrocellular carbon derived from popcorn as sulfur host for high-performance lithium-sulfur batteries

Due to the demands for high performance and ecological and economical alternatives to conventional lithium-ion batteries(Li Bs),the development of lithium-sulfur(Li-S)batteries with remarkably higher theoretical capacity(1675 m A h g-1)has become one of the extensive research focus directions worldwide.However,poor conductivity of sulfur,critical cyclability problems due to shuttle of polysulfides as intermediate products of the cathodic reaction,and large volume variation of the sulfur composite cathode upon operation are the major bottlenecks impeding the implementation of the next-generation Li-S batteries.In this work,a unique three-dimensional(3D)interconnected macrocellular porous carbon(PC)architecture decorated with metal Ni nanoparticles was synthesized by a simple and facile strategy.The as-fabricated Ni/PC composite combines the merits of conducting carbon skeleton and highly adsorptive abilities of Ni,which resulted in efficient trapping of lithium polysulfides(Li PSs)and their fast conversion in the electrochemical process.Owing to these synergistic advantageous features,the composite exhibited good cycling stability(512.3 mA h g^(-1)after 1000 cycles at 1 C with an extremely low capacity fading rate 0.03%per cycle),and superior rate capability(747.5 mA h g^(-1)at 2 C).Accordingly,such Ni nanoparticles embedded in a renewable puffed corn-derived carbon prepared via a simple and effective route represent a promising active type of sulfur host matrix to fabricate high-performance Li-S batteries.

Oxidized Nb_(2)C MXene as catalysts for lithium-sulfur batteries:Mitigating the shuttle phenomenon by facilitating catalytic conversion of lithium polysulfides

Extensive research has been devoted to lithium-sulfur(Li-S)batteries due to their overwhelming promises and advantages such as high theoretical capacity(1675 m Ah g^(-1)),extremely cost effectiveness and abundance and availability of sulfur.Nevertheless,a sluggish electrochemical kinetics of the battery limited by a slow conversion of lithium polysulfide(LiPSs)intermediates and Li PSs shuttle effect severely hinder its development towards industrial application.Herein,we designed the oxidized Nb2_(C)MXene with amorphous carbon(Nb_(2)O_(5)/C)composites as sulfur host using CO_(2)treatment to address the above issues.The Nb_(2)O_(5)/C composites with high conductivity are directly employed as sulfur hosts for Li-S battery capable to remarkably mitigate the shuttle phenomenon due to a combined effect of their Li PSs trapping ability and catalytic activity towards their accelerated conversion.Meanwhile,the unique layered structure of the composite facilitates ion transfer and accommodates the volume changes of the cathode during cycling.With this rational design,the resultant Li-S batteries exhibit superior electrochemical performance with a high initial specific capacity of 745 m Ah g^(-1)at 1.0 C and a reversible capacity of 620 m Ah g^(-1)at a high rate cycling at 3.0 C.

Defect-rich porous tubular graphitic carbon nitride with strong adsorption towards lithium polysulfides for high-performance lithium-sulfur batteries

The commercialization of the lithium-sulfur(Li-S)batteries is severely hampered by the shuttle effect and sluggish kinetics of lithium polysulfides(Li PSs).In this study,porous tubular graphitic carbon nitride(PTCN)was synthesized as the sulfur host by hydrothermal treatment,thermal shock and etching methods.By etching technology,the hollow nanotube tentacles grow on the tube wall of PTCN,the mesoporous appears on the inner wall,and a large number of nitrogen defects are introduced.The verticallyrooted hollow nanotube tentacles on the PTCN surface facilitate electron conduction for sulfur redox reactions.The hollow and porous architecture exposes plentiful active interfaces for accelerated redox conversion of polysulfide.Furthermore,the nitrogen defects in PTCN enable more excellent intrinsic conductivity,higher adsorbability and conversion catalytic activity to Li PSs.Based on the above synergetic effect,the batteries with PTCN/S cathodes realize a high discharge capacity of 504 m Ah g^(-1) at 4 C and a stable cycling behavior over 500 cycles with a low capacity decay of 0.063%per cycle.The results indicate a promising approach todesigning a high performance electrode material for Li-S batteries.

Evaluation of GOFP over four forest plots using RAMI and UAV measurements

Comparison and validation of canopy reflectance(CR)models are two important steps to ensure their reliability.Pure forest plantations are an ideal type of forest for validating CR models because of their simple background and the low variance in the crown structures which are usually assumed to be identical in most CR models.A Geometric Optical Model for Forest Plantations(GOFP)was compared using dataset in two radiation transfer model intercomparison exercise(RAMI)stands and validated using in situ dataset of detailed optical and structural data of two forest plantations in the Saihanba Forestry Center,China.The results show that(1)the tree distributions in stands described by the hypergeometric model in GOFP show good consistencies with the dataset in the two RAMI stands and measurements from the two Saihanba forest stands;and(2)the CRs simulated with GOFP are also compared well in the two RAMI stands and validated with measurements collected with unmanned aerial vehicles in the two Saihanba stands.GOFP shows a better consistency with the CR measurements than those from CR models for natual forestsbecause the tree distribution in forest plantations is described more reasonably in GOFP.

The Nord Stream pipeline gas leaks released approximately 220,000 tonnes of methane into the atmosphere

Sudden mega natural gas leaks of two Nord Stream pipelines in the Baltic Sea(Denmark)occurred from late September to early October 2022,releasing large amounts of methane into the atmosphere.We inferred the methane emissions of this event based on surface in situ observations using two inversion methods and two meteorological reanalysis datasets,supplemented with satellite-based observations.We conclude that approximately 220±30 Gg of methane was released from September 26 to October 1,2022.

Sensitivity of Estimated Total Canopy SIF Emission to Remotely Sensed LAI and BRDF Products

Remote sensing of solar-induced chlorophyll fluorescence(SIF)provides new possibilities to estimate terrestrial gross primary production(GPP).To mitigate the angular and canopy structural effects on original SIF observed by sensors(SIF_(obs)),it is recommended to derive total canopy SIF _(emission)(SIF_(total))of leaves within a canopy using canopy interception(i0)and reflectance of vegetation(R_(V)).However,the effects of the uncertainties in i_(0) and R_(V) on the estimation of SIFtotal have not been well understood.Here,we evaluated such effects on the estimation of GPP using the Soil-Canopy-Observation of Photosynthesis and the Energy balance(SCOPE)model.The SCOPE simulations showed that the R^(2) between GPP and SIF_(total) was clearly higher than that between GPP and SIFobs and the differences in R^(2)(ΔR^(2))tend to decrease with the increasing levels of uncertainties in i_(0) and RV.The resultantΔR^(2) decreased to zero when the uncertainty level in i0 and RV was~30%for red band SIF(RSIF,683 nm)and~20%for far-red band SIF(FRSIF,740 nm).In addition,as compared to the TROPOspheric Monitoring Instrument(TROPOMI)SIFobs at both red and far-red bands,SIF_(total) derived using any combination of i_(0)(from MCD15,VNP15,and CGLS LAI products)and RV(from MCD34,MCD19,and VNP43 BRDF products)showed comparable improvements in estimating GPP.With this study,we suggest a way to advance our understanding in the estimation of a more physiological relevant SIF datasets(SIF_(total))using current satellite products.