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Developing low-cost and high-efficiency bifunctional electrocatalysts for both oxygen evolution and reduction reactions is urgent to fulfill the practical application of rechargeable Zn-air batteries (ZABs). However, to explore the high catalytic performance of air electrocatalysts still remains a challenge. In response, a three-dimensionally ordered macroporous (3DOM) Co3O4 electrocatalyst is designed and synthesized through a nanocasting strategy. A well-controlled phosphorization treatment is further conducted to induce defect engineering on the resulting P-doped Co3O4–δ (3DOM P-Co3O4–δ). With the oxygen vacancy (Vo) tailoring, partial reduction from Co3+ to Co2+ is verified as the key to improving the intrinsic electrocatalytic bifunctionality. By incorporating the geometric and electronic merits, 3DOM P-Co3O4–δ possesses an ORR half-wave potential of 0.82 V and an OER overpotential of 366 mV to achieve 10 mA cm–2, which is comparable to noble-metal benchmarks. Particularly, under galvanostatic cycling measurements, ZABs using 3DOM P-Co3O4–δ containing air cathode showcase a potential gap of 0.84 V with negligible voltage fading over 250 h at 10 mA cm–2.

In recent years, the development of lithium-ion batteries (LIBs) with high energy density has become one of the important research directions to fulfill the needs of electric vehicles and smart grid technologies. Nowadays, traditional LIBs have reached their limits in terms of capacity, cycle life, and stability, necessitating their further improvement and development of alternative materials with remarkably enhanced properties. A nitrogen-containing carbon nanotube (N-CNT) host for bimetallic sulfide (NiCo2S4) is proposed in this study as an anode with attractive electrochemical performance for LIBs. The prepared NiCo2S4/N-CNT nanocomposite exhibited improved cycling stability, rate performance, and an excellent reversible capacity of 623.0 mAh g–1 after 100 cycles at 0.1 A g–1 and maintained a high capacity and cycling stability at 0.5 A g–1. The excellent electrochemical performance of the composite can be attributed to the unique porous structure, which can effectively enhance the diffusivity of Li ions while mitigating the volume expansion during the charge–discharge processes.

Due to the demands for high performance and ecological and economical alternatives to conventional lithium-ion batteries (LiBs), the development of lithium-sulfur (Li-S) batteries with remarkably higher theoretical capacity (1675 mA 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 (LiPSs) 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.

With the rapid development of flexible and wearable electronics, flexible zinc-air battery technology attracts ever-increasing attention and is considered as one of the most promising energy storage systems. However, its practical application is still at the preliminary stage. In this review, the basic battery configurations and design principles are discussed for flexible zinc-air battery, followed by challenges and recent progresses in developing each battery component, in terms of polymer electrolyte, metal anode and air cathode. An overview of flexible zinc-air battery is provided here with the aim to present a clear picture of current research directions.

Advanced host materials are requisite for both cathode and anode in the development of high-performance lithium–sulfur (Li–S) batteries. Herein, for the first time, we report a unique niobium oxide matrix with amorphous/crystalline hetero-conjunctions (A/T-Nb2O5) as a two-in-one host in a Li–S system. The heterostructure is constructed by simply regulating the calcination temperature at a modest level to generate partially-crystalized Nb2O5, rather than completely crystalline or amorphous. As the cathode matrix, the heterostructured design is unveiled, combining the preferably high sulfur affinity and fast ion transfer from the amorphous and crystalline phase, respectively, thus rendering a simultaneous stabilization and catalyzation for sulfur electrochemistry with excellent cyclability over 800 cycles and rate capability up to 3C. On the other hand, the as-developed A/T-Nb2O5 is found capable of facilitating the Li redox kinetics and uniformizing the Li nucleation/growth behaviors when applied as the anode matrix, contributing to durable Li plating/stripping at varied capacity limit up to 10 mA h cm−2. Collectively, these advantageous features are integrated into a S–A/T-Nb2O5|Li–A/T-Nb2O5 full-cell configuration, which realizes decent areal capacity, cyclability, and rate capability under a high sulfur loading of 5 mg cm−2, demonstrating an instructive paradigm for rational material engineering in Li–S batteries.

It is difficult to predict precisely the frequency response of a complex vibro-acoustic system in mid-frequency region. To overcome this deficiency, a novel hybrid stable node-based smoothed finite element method/statistical energy analysis model is proposed in this work. The whole vibro-acoustic system can be divided into a combination of a structural subsystem with statistical behavior and an acoustic subsystem with deterministic feature. The recently developed stable node-based smoothed finite element method is employed here to simulate the deterministic subsystem, and the statistical energy analysis is utilized to deal with the statistical subsystem. Based on the so-called diffuse field reciprocity relation, these two subsystems can be easily connected and coupled. Due to the introducing of gradient smoothing and compensation operation, our algorithm can significantly reduce the dispersion error compared with the traditional finite element method. Thus, it is expected that the present coupled model can provide ultra-accurate results. Numerical examples, including both benchmark and practical engineering cases, demonstrate that our algorithm works very well in mid-frequency vibro-acoustic analysis.

Over the past decade, lithium-sulfur (Li-S) batteries have been thought of as promising alternatives for the new generation of battery systems. Although the Li-S batteries possess high-theoretical energy density (2600 Wh kg-1) and capacity (1675 mAh g-1), the problems of poor electron and ion conduction, volumetric expansion, and sulfur immobilization greatly impede the wide applicability of Li-S batteries. Herein, a defect-rich multishelled Co3O4 microsphere structure doped with Fe was synthesized via a one-step hydrothermal method and subsequent thermal treatment. The unique multishelled structure provides multiple spatial confinements for lithium polysulfides trapping and buffering the volume variation during cycling. Moreover, the rich oxygen defect designed by controlled Fe doping can provide numerous catalytic sites for polysulfide redox reactions. Attributed to the synergistic effect of structural design and oxygen-defect fabrication, the sulfur composite electrode delivers a notable cycle performance, presenting a much lower capacity fading of 0.017% per cycle over 1000 cycles at 1 C and an excellent rate capability of 571.3 mAh g-1 at 5 C. This work proposes a potential approach for designing a transition metal oxide-based multishelled hollow structure combined with oxygen defect, which also offers a new perspective on high-performance Li-S batteries.

[EN] The first satellite-based global retrievals of terrestrial sun-induced chlorophyll fluorescence (SIF) were achieved in 2011. Since then, a number of global SIF datasets with different spectral, spatial, and temporal sampling characteristics have become available to the scientific community. These datasets have been useful to monitor the dynamics and productivity of a range of vegetated areas worldwide, but the coarse spatiotemporal sampling and low signal-to-noise ratio of the data hamper their application over small or fragmented ecosystems. The recent advent of the Copernicus Sentinel-5P TROPOMI mission and the high quality of its data products promise to alleviate this situation, as TROPOMI provides daily global measurements at a much denser spatial and temporal sampling than earlier satellite instruments. In this work, we present a global SIF dataset produced from TROPOMI measurements within the TROPOSIF project funded by the European Space Agency. The current version of the TROPOSIF dataset covers the time period between May 2018 and April 2021. Baseline SIF retrievals are derived from the 743¿758¿nm window. A secondary SIF dataset derived from an extended fitting window (735¿758¿nm window) is included. This provides an enhanced signal-to-noise ratio at the expense of a higher sensitivity to atmospheric effects. Spectral reflectance spectra at seven 3¿nm windows devoid of atmospheric absorption within the 665¿785¿nm range are also included in the TROPOSIF dataset as an important ancillary variable to be used in combination with SIF. The methodology to derive SIF and ancillary data as well as results from an initial data quality assessment are presented in this work. The TROPOSIF dataset is available through the following digital object identifier, This research has been supported by the European Space Agency (grant no. 4000127461/19/I-NS) and the National Aeronautics and Space Administration (grant no. NNX15AH95G)

The connection between solar-induced fluorescence (SIF) and vegetation gross primary productivity is being widely investigated across spatial, temporal, and biological scales, including: a) studies at the leaf [1], [2], plant canopy [2]–[4] or satellite pixel scale [5], [6], b) temporally with studies spanning from diurnal [7] to seasonal scales [1], [3], [5], and b) biologically with studies covering various plant functional types (PFTs), e.g., crops [4], [7], deciduous [8] or evergreen forests [1], [3], in response to different sources of stress.

Lithium–sulfur batteries render a high energy density but suffer from poor cyclic performance due to the dissolution of intermediate polysulfides. Herein, a lightweight nanoporous TiO2 and graphene oxide (GO) composite is prepared and utilized as an interlayer between a Li anode and a sulfur cathode to suppress the polysulfide migration and improve the electrochemical performance of Li/S batteries. The interlayer can capture the polysulfides due to the presence of oxygen functional groups and formation of chemical bonds. The hierarchically porous TiO2 nanoparticles are tightly wrapped in GO sheets and facilitate the polysulfide storage and chemical absorption. The excellent adhesion between TiO2 nanoparticles and GO sheets resulted in enhanced conductivity, which is highly desirable for an efficient electron transfer process. The Li/S battery with a TiO2/GO-coated separator exhibited a high initial discharge capacity of 1102.8 mAh g−1 and a 100th cycle capacity of 843.4 mAh g−1, which corresponds to a capacity retention of 76.48% at a current rate of 0.2 C. Moreover, the Li/S battery with the TiO2/GO-coated separator showed superior cyclic performance and excellent rate capability, which shows the promise of the TiO2/GO composite in next-generation Li/S batteries.

In this work, we report a new type of aqueous sodium-ion batteries employing Na4Mn9O18/carbon nanotube/reduced graphene oxide (NMO/CNT/RGO) composite as a cathode material while zinc metal as anode material. The NMO/CNT/RGO composites are prepared by a spray drying method and possess a microsphere structure. Addition of RGO and CNT significantly improve the electrical conductivity of NMO composite materials. A stable network skeleton structure was formed in the interior and was beneficial to relieve stress and strain caused due to sodium ion movement and significantly improve the electrochemical performance of cathode materials. The initial reversible discharge specific capacity of the ternary composite electrode is 96.2 mAh g−1 at 4 C, and retained 68% capacity after 150 cycles (discharge capacity 65.8 mAh g−1). NMO/CNT/RGO composites have an excellent rate performance and high cycle capacity.

Despite the high theoretical capacity (2600 Wh kg–1) of a sulfur cathode, lithium/sulfur (Li/S) batteries still face several serious challenges on the road to commercial success. Herein, a unique t...

Herein, magnesium/aluminum (Mg/Al) composite rods were prepared by compound casting and multi-pass warm caliber rolling, and the effect of caliber rolling on the evolution of the interfacial microstructure and mechanical properties of the Mg/Al compound castings was investigated. The results reveal a uniform interface, which can be divided into three layers consisting of Al3Mg2, Al12Mg17 and (Al12Mg17 + Mg) eutectic structure, was formed during the compound casting. Afterwards, the brittle reaction layer fragmented during the rolling process, and was effectively eliminated after 12 passes. Meanwhile, the fresh Al and Mg bases squeezed out and bonded together under the rolling force. The interface formed after the final rolling process had no visible intermetallic compounds. Further, an inhomogeneous deformation in the Mg and Al bases was observed during the rolling process. Initially, the Al clad layer accommodated a larger proportion of the plastic deformation. With increasing number of passes, however, the strain in the Mg core layer increased and, after 12 passes, the deformation of both layers tended to be equivalent. The strength of the Mg/Al composite rod increased gradually and the ultimate tensile stress reached a value of 247 MPa after 12 passes.

The practical application of lithium/sulfur (Li/S) batteries is hindered by the migration of soluble polysulfides (Li2S n , 4 ≤ n ≤ 8) from cathode to anode, leading to poor electrochemical stability of the cell. To address this issue, in the present study, a TiO2/porous carbon (TiO2/PC) composite-coated Celgard 2400 separator was successfully fabricated and used as a polysulfide barrier for the Li/S battery. In TiO2/PC, the highly conductive PC with three-dimensional ordered porous structure physically constrains polysulfides and at the same time serves as an additional upper current collector. On the other hand, the TiO2 on the surface of PC chemically adsorbed polysulfides during the charge/discharge process. Due to the physical and chemical adsorption properties of TiO2/PC composite coating layer, an initial discharge capacity of 926 mAh g−1 at 0.1 C and a low fading rate (75% retention after 150 cycles) were achieved. Moreover, in the rate capability test, the discharge capacity for the TiO2/PC-modified Li/S battery was recovered to 728 mAh g−1 at 0.1 C after high-rate cycling and remained ~ 88% of the initial reversible capacity.

Satellite remote sensing has been widely used in the last decades for agricultural applications, both for assessing vegetation condition and for subsequent yield prediction. Existing remote sensing-based methods to estimate gross primary productivity (GPP), which is an important variable to indicate crop photosynthetic function and stress, typically rely on empirical or semi-empirical approaches, which tend to over-simplify photosynthetic mechanisms. In this work, we take advantage of all parallel developments in mechanistic photosynthesis modeling and satellite data availability for an advanced monitoring of crop productivity. In particular, we combine process-based modeling with the soil-canopy energy balance radiative transfer model (SCOPE) with Sentinel-2 and Landsat 8 optical remote sensing data and machine learning methods in order to estimate crop GPP. With this approach, we by-pass the need for an intermediate step to retrieve the set of vegetation biophysical parameters needed to accurately model photosynthesis, while still accounting for the complex processes of the original physically-based model. Several implementations of the machine learning models are tested and validated using simulated and flux tower-based GPP data. Our final neural network model is able to estimate GPP at the tested flux tower sites with r2 of 0.92 and RMSE of 1.38 gC d−1 m−2, which outperforms empirical models based on vegetation indices. The first test of applicability of this model to Landsat 8 data showed good results (r2 of 0.82 and RMSE of 1.97 gC d−1 m−2), which suggests that our approach can be further applied to other sensors. Modeling and testing is restricted to C3 crops in this study, but can be extended to C4 crops by producing a new training dataset with SCOPE that accounts for the different photosynthetic pathways. Our model successfully estimates GPP across a variety of C3 crop types and environmental conditions even though it does not use any local information from the corresponding sites. This highlights its potential to map crop productivity from new satellite sensors at a global scale with the help of current Earth observation cloud computing platforms.

Transition metal oxide Cu2O anode is still not meeting the current market demands due to the low theoretical capacity and poor cycle stability. We herein report the synthesis of a nanoporous GeO2/Cu/Cu2O network by a straightforward dealloying method. The resulting material possesses high porosity which served to alleviate the stress incurred during lithiation/delithiation volume variation and presents good conductivity for fast electron transfer. Enhanced electrochemical performance is observed when measured as an anode material, delivering 715 mAh g−1 at 200 mA g−1 after 50 cycles and offered 504 mAh g−1 even at a high current density of 1600 mA g−1 after 150 cycles. Furthermore, the material also demonstrates excellent rate performance of 812, 782, 741, 695, 635 and 552 mAh g−1 at 100, 200, 500, 800, 1600 and 3200 mA g−1 current densities, respectively. The enhanced Li storage performances could be ascribed to the reticular ligament with high porosity, the increased conductivity by Cu as well as the improved capacity from GeO2. Moreover, this work provides us a new material design strategy to fabricate various porous composite anodes with high capacity through a straightforward dealloying method in future for lithium-ion battery applications.

Herein, we demonstrate a facile synthesis process to fabricate and deposit flower-like CuS/graphene nanocomposite on a multi-functional separator for efficient immobilization of polysulfides of lithium/sulfur (Li/S) batteries. Admirably, as-prepared CuS/graphene composite endows enriched oxygen-functional groups and excellent electrical conductivity for cathode area. The introduction of CuS/graphene-coated separator effectively reduced the dissolution of lithium polysulfides as well as enhanced the integrity of the sulfur cathode for Li/S batteries. The cell with these modified separator delivered an enviable discharge capacity of 1302 mAh g−1 at 0.2 C, as well as an excellent reversible capacity of 760 mAh g−1 after 100 cycles. Furthermore, an outstanding rate capability of 568 mAh g−1 at 3.0 C has been achieved in the cell with CuS/graphene-coated separator. The results reveal that CuS/graphene-coated separator shows an admirable potentiality to boost the performance of next-generation Li/S batteries.

Lithium-sulfur (Li-S) batteries represent one of the most promising battery techniques in 21st century. However, the practical implementation of Li-S batteries is impeded by several intractable obstacles including the poor conductivity of sulfur, shuttling behaviour of polysulfides intermediates, and large volume change during sulfur lithiation. Thus, the rational design and morphological control of sulfur cathode paves the way to Li-S batteries practicalizations. Herein, we develop a blackberry-like hollow graphene sphere through spray drying method as a promising sulfur host for Li-S batteries. Attributed to the uniform sulfur distribution, fast reaction kinetics, and excellent sulfur immobilization, the S-HGS composite electrode achieves a highly reversible capacity of 780 mAh g−1, a great rate capability as well as cyclability without adding additives.

A three-dimensionally (3D) ordered macro/mesoporous carbon (3DOMC) is synthesized by one-step template method as a TiO2 supporter, and this TiO2/3DOMC hybrid plays the role of immobilizers and can limit any polysulfides from escaping the cathode. The TiO2/3DOMC exhibits high pore volume and specific surface area, accommodating up to 73.2 wt% in sulfur content. As a sulfur host, S/TiO2/3DOMC composite was able to delivered 1105 mAh g−1 on first discharge and 695 mAh g−1 after 150 cycles at a current rate of 0.5 C. Even though at 2 C this material was able to keep a capacity of 551 mAh g−1. We attribute the superior performance to the good conductivity and structural restriction of carbon and the intense electrostatic attraction between metal-oxygen bond and polysulfides to encapsulate sulfur of the TiO2/3DOMC.

With the development of smart electronics, a wide range of techniques have been considered for efficient co-integration of micro devices and micro energy sources. Physical vapor deposition (PVD) by means of thermal evaporation, magnetron sputtering, ion-beam deposition, pulsed laser deposition, etc., is among the most promising techniques for such purposes. Layer-by-layer deposition of all solid-state thin-film batteries via PVD has led to many publications in the last two decades. In these batteries, active materials are homogeneous and usually binder free, which makes them more promising in terms of energy density than those prepared by the traditional powder slurry technique. This review provides a summary of the preparation of cathode materials by PVD for all solid-state thin-film batteries. Cathodes based on intercalation and conversion reaction, as well as properties of thin-film electrode–electrolyte interface, are discussed.

State-of-the-art distributed in-memory datastores (FaRM, FaSST, DrTM) provide strongly-consistent distributed transactions with high performance and availability. Transactions in those systems are fully general; they can atomically manipulate any set of objects in the store, regardless of their location. To achieve this, these systems use complex distributed transactional protocols. Meanwhile, many workloads have a high degree of locality. For such workloads, distributed transactions are an overkill as most operations only access objects located on the same server -- if sharded appropriately. In this paper, we show that for these workloads, a single-node transactional protocol combined with dynamic object re-sharding and asynchronously pipelined replication can provide the same level of generality with better performance, simpler protocols, and lower developer effort. We present Zeus, an in-memory distributed datastore that provides general transactions by acquiring all objects involved in the transaction to the same server and executing a single-node transaction on them. Zeus is fault-tolerant and strongly-consistent. At the heart of Zeus is a reliable dynamic object sharding protocol that can move 250K objects per second per server, allowing Zeus to process millions of transactions per second and outperform more traditional distributed transactions on a wide range of workloads that exhibit locality., Comment: Sixteenth European Conference on Computer Systems

Rational construction of sulfur electrodes is essential in pursuit of practically viable lithium–sulfur (Li–S) batteries. Herein, bimetallic NiCo‐layered double hydroxide (NiCo‐LDH) with a unique hierarchical micro‐nano architecture is developed as an advanced sulfur reservoir for Li–S batteries. Compared with the monometallic Co‐layered double hydroxide (Co‐LDH) counterpart, the bimetallic configuration realizes much enriched, miniaturized, and vertically aligned LDH nanosheets assembled in hollow polyhedral nanoarchitecture, which geometrically benefits the interface exposure for host–guest interactions. Beyond that, the introduction of secondary metal intensifies the chemical interactions between layered double hydroxide (LDH) and sulfur species, which implements strong sulfur immobilization and catalyzation for rapid and durable sulfur electrochemistry. Furthermore, the favorable NiCo‐LDH is architecturally upgraded into closely packed micro‐nano clusters with facilitated long‐range electron/ion conduction and robust structural integrity. Due to these attributes, the corresponding Li–S cells realize excellent cyclability over 800 cycles with a minimum capacity fading of 0.04% per cycle and good rate capability up to 2 C. Moreover, highly reversible areal capacity of 4.3 mAh cm−2 can be achieved under a raised sulfur loading of 5.5 mg cm−2. This work provides not only an effective architectural design but also a deepened understanding on bimetallic LDH sulfur reservoir for high‐performance Li–S batteries., A unique NiCo‐LDH@rGO micro‐nano hierarchical composite is developed as a synergistic sulfur immobilizer and promoter to realize high‐efficiency lithium–sulfur battery chemistry. The unique architecture of NiCo‐LDH@rGO and its strong chemical interactions with the intermediate polysulfides afford large space for sulfur, enable expedite ion/mass transfer, and effectively restrain and catalyze the conversion of polysulfide.

Due to huge volume expansion and poor electrical conductivity, the commercial application of the promising Germanium (Ge) anode is restrained in lithium ion battery (LIB) field. Generally, conductive metals can improve the electron mobility in Ge. In that way, whether active materials or conductive metals account for a higher proportion in the anode is controversial in this field and needs to be clarified urgently. Herein, three Ge-based anodes with different ratios in conductive Ag are fabricated by a facile melt spinning and one-step dealloying method. It is found that Ag nanoparticles embedded three-dimensional nanoporous Ge (Ag/np-Ge) electrode with high active material ratio exhibits the best cycling stability among tested samples, delivering a high capacity of 953 mAh g−1 after 100 cycles at a current density of 100 mA g−1 and an excellent reversible capacity of 522 mAh g−1 after 200 cycles even at the high current density of 1000 mA g−1. The enhanced cycling stability can be attributed to the synergistic effect of nanoporous network-like structure and embedded Ag nanoparticles. A dramatical increase in electrical conductivity and activity of Ge by doping of Ag is confirmed by density functional theory (DFT) calculations. The work provides us an idea to rationally design the three-dimensional structure of active materials assisting with a proper ratio of conductive metals, which may promote the development of promising Ge anodes for LIBs with excellent cycling stability.

Germanium (Ge)‐based materials have been considered as potential anode materials for sodium‐ion batteries owing to their high theoretical specific capacity. However, the poor conductivity and Na+ diffusivity of Ge‐based materials result in retardant ion/electron transportation and insufficient sodium storage efficiency, leading to sluggish reaction kinetics. To intrinsically maximize the sodium storage capability of Ge, the nitrogen doped carbon‐coated Cu3Ge/Ge heterostructure material (Cu3Ge/Ge@N‐C) is developed for enhanced sodium storage. The pod‐like structure of Cu3Ge/Ge@N‐C exposes numerous active surface to shorten ion transportation pathway while the uniform encapsulation of carbon shell improves the electron transportation, leading to enhanced reaction kinetics. Theoretical calculation reveals that Cu3Ge/Ge heterostructure can offer decent electron conduction and lower the Na+ diffusion barrier, which further promotes Ge alloying reaction and improves its sodium storage capability close to its theoretical value. In addition, the uniform encapsulation of nitrogen‐doped carbon on Cu3Ge/Ge heterostructure material efficiently alleviates its volume expansion and prevents its decomposition, further ensuring its structural integrity upon cycling. Attributed to these unique superiorities, the as‐prepared Cu3Ge/Ge@N‐C electrode demonstrates admirable discharge capacity, outstanding rate capability and prolonged cycle lifespan (178 mAh g−1 at 4.0 A g−1 after 4000 cycles)., Nitrogen doped carbon‐coated Cu3Ge/Ge heterostructure is developed as anode material for fast and longevous sodium storage. Cu3Ge/Ge heterostructure efficiently promotes the Na+ diffusion and electron conduction in the composite, which enhances the sodium storage capability of Ge and accelerates its redox reaction kinetics. Attributed to the structural superiorities, a remarkable discharge capacity, superb rate capability and enhanced cyclic stability can be realized.

Hematite is recognized as an excellent photocatalyst for photoelectrochemical photoanodes for water oxidation because of its favorable band gap, excellent anti-photocorrosion and structural stability in alkaline solution. However, slow charge transport and fast carrier recombination in the bulk and at the hematite photoanode/electrolyte interface, have limited its applications for water splitting. Herein, we report a highly efficient hematite/ferrhydrite (Fh) core-shell photoanode system, consisting of hematite (α-Fe2O3) semiconductor nanorods which dramatically enhance light harvesting, and ferrhydrite as the hole-storage shell. Our integrated hematite/ferrhydrite core-shell photoanode shows 2.7 times increased photo-current density under simulated sun light irradiation.

Near-infrared (NIR)-light responsive graphene have been shown exciting effect on cancer photothermal ablation therapy. Herein, we report on the preparation of Fe3O4-decorated hollow graphene microspheres (rGO@Fe3O4) by a facile spray drying and coprecipitation method for the magnetically targeted and NIR-responsive chemo-photothermal combination therapy. The microspheres displayed very high specific surface area (~ 120.7 m2 g−1) and large pore volume (~ 1.012 cm3 g−1), demonstrating distinct advantages for a high loading capacity of DOX (~ 18.43%). NIR triggered photothermal effect of the rGO@Fe3O4 microspheres responded in an on-off manner and induced a high photothermal conversion efficiency. Moreover, The Fe3O4 on the microspheres exhibited an excellent tumor cells targeting ability. The chemo-photothermal treatment based on rGO@Fe3O4/DOX showed superior cytotoxicity towards Hela cells in vitro. Our studies indicated that rGO@Fe3O4/DOX microcapsules have great potential in combined chemo-photothermal cancer treatment.

Quantifying global photosynthesis remains a challenge due to a lack of accurate remote sensing proxies. Solar-induced chlorophyll fluorescence (SIF) has been shown to be a good indicator of photosynthetic activity across various spatial scales. However, a global and spatially challenging estimate of terrestrial gross primary production (GPP) based on satellite SIF remains unresolved due to the confounding effects of species-specific physical and physiological traits and external factors, such as canopy structure or photosynthetic pathway (C-3 or C-4). Here we analyze an ensemble of far-red SIF data from OCO-2 satellite and ground observations at multiple sites, using the spectral invariant theory to reduce the effects of canopy structure and to retrieve a structure-corrected total canopy SIF emission (SIFtotal). We find that the relationships between observed canopy-leaving SIF and ecosystem GPP vary significantly among biomes. In contrast, the relationships between SIFtotal and GPP converge around two unique models, one for C-3 and one for C-4 plants. We show that the two single empirical models can be used to globally scale satellite SIF observations to terrestrial GPP. We obtain an independent estimate of global terrestrial GPP of 129.56 +/- 6.54 PgC/year for the 2015-2017 period, which is consistent with the state-of-the-art data- and process-oriented models. The new GPP product shows improved sensitivity to previously undetected 'hotspots' of productivity, being able to resolve the double-peak in GPP due to rotational cropping systems. We suggest that the direct scheme to estimate GPP presented here, which is based on satellite SIF, may open up new possibilities to resolve the dynamics of global terrestrial GPP across space and time.

For investigating the influence of coexisting ions (K+, Mg2+, Ca2+ and SO42−), temperature and their synergistic effect on energy generation by reverse electrodialysis, two series of cells dividing with Yadeshi membranes are fed with different solutions at 10 °C, 25 °C and 40 °C. The presence of K+, Mg2+, Ca2+ and SO42− results in lower open circuit voltage, higher internal resistance and lower maximum power density, and the influence order of ions coexisting with NaCl is Ca2+ > Mg2+ (>SO42−) > K+. With the temperature risen, the open circuit voltage and the internal resistance show a trend of increase and decrease respectively, resulting in a bigger power density. Based on the synergistic effect of coexisting ions and temperature, the maximum power density of the pure NaCl system shows a greater increment (0.15 W m−2) than that of NaCl-CaCl2 (0.10 W m−2) and NaCl-MgCl2 (0.11 W m−2) systems when temperature increases from 10 °C to 40 °C. Furthermore, the transport quantities of ions in each system increased with temperature at different degrees, and the uphill of Ca2+ and Mg2+ was more obvious, which can reasonably explain the different effects of temperature on the maximum power density. Moreover, these results are further verified when simulated concentrated seawater is used for both the Yadeshi- and Fujifilm membranes, and the Fujifilm shows better energy generation performance mainly due to a lower internal resistance.

A series of novel visible light driven all-solid-state Z-scheme BiOBr0.3I0.7/Ag/AgI photocatalysts were synthesized by facile in situ precipitation and photo-reduction methods. Under visible light irradiation, the BiOBr0.3I0.7/Ag/AgI samples exhibited enhanced photocatalytic activity compared to BiOBr0.3I0.7 and AgI in the degradation of methyl orange (MO). The optimal ratio of added elemental Ag was 15%, which degraded 89% of MO within 20 min. The enhanced photocatalytic activity of BiOBr0.3I0.7/Ag/AgI can be ascribed to the efficient separation of photo-generated electron–hole pairs through a Z-scheme charge-carrier migration pathway, in which Ag nanoparticles act as electron mediators. The mechanism study indicated that ·O2 − and h+ are active radicals for photocatalytic degradation and that a small amount of ·OH also participates in the photocatalytic degradation process.

A hierarchically porous TiO2 matrix was synthesized via a facile dealloying method for high-performance lithium/sulfur batteries. The dealloying processing forms an interconnected porous structure with high porosity (0.39 cm3 g−1) and large surface area (82.39 m2 g−1). The specific structure provides effective contact between sulfur and host material, thus trapping the polysulfide intermediates and suppressing the shuttle effect. The resulting S/TiO2 composites exhibit excellent cycling and rate performance, which maintained 641 mAh g−1 at 200th cycle at 0.2 C, and 600 mAh g−1 at 2.5 C. The coulombic efficiency remains at nearly 99% except for the first cycle. This excellent electrochemical performance of S/TiO2 composites can be attributed to the strong electrostatic attraction between metal-oxygen bond and polysulfides and structural restriction to encapsulate sulfur of hierarchically porous TiO2.

To enhance the electrochemical performance of the lithium/sulfur batteries, a novel interlayer was prepared by coating the slurry of PPy/ZnO composite onto the surface of a separator. Owing to a three-dimensional hierarchical network structure, PPy/ZnO composite serves as a polysulfide diffusion absorbent that can intercept the migrating soluble polysulfides to enhance the electrochemical performance of the Li/S batteries. The specific capacity of the cell with PPy/ZnO interlayer remained at 579 mAh g−1 after 100 cycles at 0.2 C. This interlayer can provide novel avenues for the commercial applications of Li/S batteries. Electronic supplementary material The online version of this article (10.1186/s11671-018-2724-x) contains supplementary material, which is available to authorized users.

It is important to understand how sun-sensor geometry affects satellite sun -induced fluorescence (SIF) in order to take full advantage of these measurements, particularly given their close relationship with gross primary production (GPP). A recent paper by Li et al. (2018) presented results on the relationship between OCO-2 SIF and GPP from 64 flux sites. Similar to Sun et al. (2017), this study suggested a nearly universal rather than biome-specific SIF-GPP relationship across biomes though a higher slope was found for C4 plants. Their results are distinct from previous studies. We argue that the universal relationship may be biased by not separating SIF data from three observation modes that have different sensor view zenith angles.

In this work, a series of efficient visible-light-driven WO3/Cu (II) nanofiber photocatalysts, with superior photocatalytic activities for the degradation of dyes and aniline, were prepared by electrospinning and impregnation methods. The impregnation method brought about homogeneous distribution of Cu (II) species on the surface of WO3 nanofibers. The prepared WO3/Cu (II) nanofiber photocatalysts exhibited enhanced visible-light absorption and reduced charge recombination, as compared to pure WO3 nanofibers, due to the interfacial charge transfer (IFCT) effect between the Cu (II) species and WO3. The combined benefits of the grafting Cu (II) species on the surface of WO3, in terms of optical, surface, and texture properties, led to a significant improvement in the photocatalytic activity for the degradation of Rhodamine B (Rh B) and aniline under conditions of visible light irradiation. Upon the irradiation with visible light in the presence of WO3/Cu (II)-2% photocatalyst, the concentration of Rhodamine B (Rh B) decreased from 10 mg/L to 1.5 mg/L, and that of aniline solution decreased from 5 mg/L to 0.728 mg/L over a period of 3 h. And after running five cycles, the concentration of aniline solution could decrease from 5 mg/L to 0.89 mg/L by WO3/Cu (II)-2% photocatalyst.

Nitrogen-doped carbon nanotubes coated with zinc oxide nanoparticles (ZnO@NCNT) were prepared via a sol–gel route as sulfur encapsulator for lithium/sulfur (Li/S) batteries. The electrochemical properties of the S/ZnO@NCNT composite cathode were evaluated in Li/S batteries. It delivered an initial capacity of 1032 mAh·g−1 at a charge/discharge rate of 0.2C and maintained a reversible capacity of 665 mAh·g−1 after 100 cycles. The coulombic efficiency of the cathode remains unchanged above 99%, showing stable cycling performance. X-ray photoelectron spectroscopy analysis confirmed the formation of S–Zn and S–O bonds in the composite. This indicates that an enhanced cycling and rate capability of the S/ZnO@NCNT composite could be ascribed to advantages of the ZnO@NCNT matrix. In the composite, the active ZnO-rich surfaces offer a high sulfur-bonding capability and the NCNT core acts as a conductive framework providing pathways for ion and electron transport. The as-prepared S/ZnO@NCNT composite is a promising cathode material for Li/S batteries.

Dissimilar joining of magnesium and aluminum using a compound casting process was investigated in the present work. For the first time, a Ni interlayer prepared by plasma spraying was inserted between the two base metals to improve the interfacial characteristics. Examination of the interfacial regions using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe microanalysis, and X-ray diffraction revealed the formation of a three-layered interface between Mg and Al without the interlayer. The thickness of the interface was approximately 600 μm when the casting was performed at 700 °C and increased with increasing casting temperature. However, with the addition of the Ni interlayer, the Al-Mg reaction was successfully prevented, and metallurgical bonding between the Ni interlayer and two base metals was achieved at a casting temperature of 700 °C. Upon increasing this temperature, Mg-Ni and Al-Ni intermetallics were generated at the separate interfaces. The shear strength of the Mg/Al bimetallic castings with the Ni interlayer was substantially improved compared with that of the direct Mg/Al joint, with a maximum value of 25.4 MPa achieved at 700 °C. Fracture occurred mainly along the Mg/Ni interface for the Mg/Ni/Al multilayer structure castings.

Herein, we report a three-dimensionally (3D) ordered macro-/mesoporous carbon (3DOM-mC) as the ZnO nanoparticles support for the anode material in lithium-ion batteries (LIBs). The 3DOM-mC is synthesized by the typical dual-templating method that combines the hard-templating (silica opal as template) and soft-templating techniques using resol (phenol/formaldehyde) as the carbon source. The prepared 3DOM-mC material having ordered interconnected macropores and mesopores is then applied to support ZnO nanoparticles to form the ZnO/3DOM-mC composite via a simple in situ solution growth approach. In the ZnO/3DOM-mC composite, the ZnO nanoparticles (∼4.5 nm) are evenly dispersed on the macropore walls of the 3DOM-mC. The ZnO/3DOM-mC composite (40 wt% ZnO loading) anode shows an enhanced LIB performance delivering a specific capacity of 973.3 mAh g−1 after 100 cycles and 1396.6 mAh g−1 after 300 cycles at 0.1 C. This good electrochemical performance of the ZnO/3DOM-mC is ascribed to the ordered interconnected macropores of the 3DOM-mC that can provide the rapid diffusion of Li ions and electrolytes and the ordered mesopores that can buffer the volume expansion of ZnO during the cycling operation.

Porous three-dimensional reduced graphene oxide (3D-RGO) was successfully synthesized. After being loaded with sulfur, the as-obtained 3D-S-RGO composite was used as a cathode for Li-S batteries. Due to its unique 3D-structured porous carbon layers with a high surface area, a high sulfur loading (75.8%) was achieved. More importantly, its 3D structure can also serve as a polysulfide storeroom to relieve the shuttle effect. Therefore, compared with regular sulfur-loaded reduced graphene oxide (S-RGO), the 3D-S-RGO cathode exhibits a greatly improved discharge capacity and cycling stability. The 3D-S-RGO cathode delivers an initial discharge capacity of 1140 mAh g−1 at 0.2 C and remains at 790 mAh g−1 after 200 cycles. This study shows that the 3D structure is essential for improving the performance of graphene-based cathodes in Li-S batteries.

The terrestrial carbon and water cycles are coupled through a multitude of connected processes among soil, roots, leaves, and the atmosphere. The strength and sensitivity of these couplings are not yet well known at the global scale, which contributes to uncertainty in predicting the terrestrial water and carbon budgets. We now have synchronous, global-scale satellite observations of critical terrestrial carbon and water cycle components: solar-induced chlorophyll fluorescence (SIF) and soil moisture. We used these observations within the framework of a global terrestrial biosphere model (Simplified Simple Biosphere Model version 2.0, SSiB2) to investigate carbon-water coupling processes. We updated SSiB2 to include a mechanistic representation of SIF and tested the sensitivity of model parameters to improve the simulation of both SIF and soil moisture with the ultimate objective of improving the first-order terrestrial carbon component, gross primary production. Although several vegetation parameters, such as leaf area index and the green leaf fraction, improved the simulated SIF, and several soil parameters, such as hydraulic conductivity, improved simulated soil moisture, their effects were mainly limited to their respective cycles. One root-mean-square error parameter emerged as the key coupler between the carbon and water cycles: the wilting point. Updates to the wilting point significantly improved the simulations for SIF and gross primary production although substantial mismatches with the satellite data still existed. This study demonstrates the value of synchronous global measurements of the terrestrial carbon and water cycles in improving the understanding of coupled carbon-water cycles.

Si nanowires (SiNWs) and graphite-like carbon nitride (g-C3N4) are highly promising materials for solar water splitting. In this work, n-type SiNWs (n-SiNWs) are obtained via metal-catalyzed electroless etching. To improve the photoelectrochemical performance of the n-SiNWs, g-C3N4 is deposited on their surface as a coating layer (n-SiNW/g-C3N4). Furthermore, to increase the density of active sites in g-C3N4, barbituric acid (BA) is introduced into precursors before the layer deposition. The n-SiNW/g-C3N4 photoanode shows a negative shift of the onset potential as compared to the bare n-SiNWs. Moreover, a 50% enhancement in the photocurrent density at 1.6V vs. RHE is achieved on the BA-modified n-SiNW/g-C3N4 as compared to the pristine n-SiNW/g-C3N4. Keywords: Water splitting, Si nanowires, Graphite-like carbon nitride, Core/shell nanostructure, Copolymerization modification

A novel three-dimensionally (3D) ordered hierarchically porous polypyrrole (3DOHPPy) is successfully synthesized via a simple chemical polymerization method by using silica colloidal crystals as templates. The 3DOHPPy possesses a large BET specific surface area (118.5 m2 g−1), 3D ordered interconnected macropores (240 nm) and mesopores (2–3 nm) on the macropore walls. The sulfur/3DOHPPy (S/3DOHPPy) composite is prepared by a solution-diffusion route followed by low-temperature heat treatment and studied as a cathode material for the lithium/sulfur (Li/S) battery. The resulting S/3DOHPPy cathode shows a high specific discharge capacity of 751 mAh g−1 even after 100 cycles at 0.1 C and great rate capability. The superior electrochemical property of the S/3DOHPPy composite is ascribed to the unique hierarchical structure of 3DOHPPy with ordered interconnected macropores that benefit enhanced mass transfer and the small mesopores on the macropore walls that can immobilize the sulfur and polysulfides produced during the discharge/charge processes.

Estimating terrestrial gross primary production is an important task when studying the carbon cycle. In this study, the ability of a two-leaf light use efficiency model to simulate regional gross primary production in China was validated using satellite Global Ozone Monitoring Instrument - 2 sun-induced chlorophyll fluorescence data. The two-leaf light use efficiency model was used to estimate daily gross primary production in China's terrestrial ecosystems with 500-m resolution for the period from 2007 to 2014. Gross primary production simulated with the two-leaf light use efficiency model was resampled to a spatial resolution of 0.5° and then compared with sun-induced chlorophyll fluorescence. During the study period, sun-induced chlorophyll fluorescence and gross primary production simulated by the two-leaf light use efficiency model exhibited similar spatial and temporal patterns in China. The correlation coefficient between sun-induced chlorophyll fluorescence and monthly gross primary production simulated by the two-leaf light use efficiency model was significant (p

Magnesium and aluminium were joined through diffusing bonding with a Ni interlayer prepared by plasma spraying for the first time. Examination of the microstructure and phase constitution of interf...

A series of barbituric acid doped carbon nitride (CN-BA) photocatalysts were successfully prepared by copolymerizing dicyandiamide with barbituric acid (BA). Under AM1.5 simulated sunlight, CN-BA photocatalysts exhibit enhanced photocatalytic activity compared to pure carbon nitride for the degradation of aniline. The highest activity is obtained with 2% doped CN-BA photocatalyst. Results on the photodegradation of aniline indicate that for the optimized CN-BA photocatalyst, the concentration of aniline solution was reduced gradually from 16 mg/L to 1.354 mg/L in 2 h. This corresponds to a 6 times higher photodegradation efficiency than pure carbon nitride samples. The enhanced photocatalytic activity of CN-BA relies on the enhanced surface area, the higher light absorption and the reduced recombination of the photo-generated electron-hole pairs. This interpretation results from multiple characterizations with EPR, BET, N2 adsorption, Solid-state 13C NMR, UV–vis DRS, FESEM, and TEM. Under simulated sunlight irradiation, CN-BA is excited and generates electron-hole pairs. The photo-generated electrons in the CN-BA conduction band react with the molecular oxygen to form O2−. Part of the O2− transforms into OH, which further oxides aniline. Meanwhile, photo-generated holes in the valence band of CN-BA can benefit to the formation of OH or directly oxide aniline.

Gel polymer electrolytes (GPE) consisting of a solution of lithium (trifluoromethane)sulfonimide (LiTFSI) dispersed in poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methyl methacrylate) (PMMA)/poly(N-isopropylacrylamide) (PNIPAM) matrix were prepared. Effect of montmorillonite clay mineral additives to stability and electrochemical performance was studied. GPEs exhibited up to 800 wt% electrolyte uptake, high electrochemical and thermal dimensional stability compared to Celgard separator. Li/S cells assembled with S/C composite cathode and PVDF-HFP/PMMA/PNIPAM GPE delivered initial discharge capacities of 1,300 and 850 mAh g −1 in the first and 15th cycles at 0.1 C, respectively, along with high coulombic efficiency (about 100 %) over 100 cycles. The coulombic efficiency was attributed to the suppression of shuttle effect by the gel polymer electrolyte leading to the higher sulfur utilization in the cell

TiO 2 anode presents a stable cycling performance but relatively low theoretical capacity, which has hindered its applications in high-performance Li-ion batteries (LIBs). For improving the Li storage properties, novel TiO 2 /Fe 2 O 3 composite with a porous “slice on slice” structure was prepared via a facile de-alloying method. The composite delivers a reversible capacity of 838.8 mAh g −1 after 400 cycles at a current density of 200 mA g −1 and maintaining a discharge capacity of 339 mAh g −1 even at 2 A g −1 . The improved Li storage property could be ascribed to the synergistic effects of the two active materials. Especially, the reduction products of Fe 0 at the interface between TiO 2 and Fe 2 O 3 can facilitate the reversibility of reactions and further result in a high reversible capacity.

A novel free-standing Na4Mn9O18/reduced graphene oxide (NMO-RGO) composite was successfully prepared by a facile vacuum filtration technique. Scanning and transmission electron microscopy studies revealed formation of a film with needle-like Na4Mn9O18 homogeneously distributed and anchored on the RGO matrix. A sodium rechargeable hybrid aqueous battery with this novel cathode and zinc anode was first investigated and reported. The NMO-RGO film delivered a reversible discharge capacity of about 83 mAh g−1 when cycled galvanostatically at a current density of 0.1 A g−1, which was for about 78% higher than that of Na4Mn9O18 prepared by a slurry casting technique. This significant enhancement of electrochemical properties of NMO-RGO was due to the presence of graphene sheets in this free-standing composite cathode. These sheets form an agile substrate with a high conductivity to guarantee a successive electronic conduction channels in the electrode. In the same time, such composition and structure enables accommodation of the volume changes of Na4Mn9O18 during sodium insertion-extraction.

In this work, we prepared the nitrogen-doped graphitized porous carbon with embedded nickel-iron alloy nanoparticles (NiFe@NC) as a sulfur host for lithium-sulfur (Li-S) batteries via a stepwise coating-calcining process of metal-organic framework (MOF) precursors. In the composite, the nitrogen-doped graphitized porous carbon possesses good electronic conductivity and physical adsorption capability for soluble lithium polysulfides (LiPSs). Furthermore, the polar NiFe alloy provides the active sites to anchor the LiPSs and effectively promote the redox conversion kinetics of these intermediates. To confirm this, the density functional theory (DFT) calculations were applied to demonstrate that there is sufficient binding energy between the NiFe alloy and LiPSs. Owing to the above-mentioned benefits, the batteries with the S/NiFe@NC cathode deliver a high initial reversible capacity (1224 mA h g−1 at 0.2 C) along with a stable cycling ability (565 mA h g−1 at 1 C after 500 cycles). Our findings provide insights towards building the novel sulfur-host materials for advanced Li-S batteries.