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Increasing the availability of π-electron in graphitic carbon nitride (g-C3N4) can reduce the band gap and thus enhance the photocatalytic hydrogen (H2) generation activity upon exposure to visible light. However, such strategy has not yet been largely applied to increase the H2 generation of g-C3N4. Herein, we successfully increased the amount of π-electron in g-C3N4 by incorporating π-electron-rich benzene rings through copolymerization of melamine and trimesic acid in air. The incorporation of benzene rings not only extends the light absorption of g-C3N4 to 650 nm, but also improves the electrical conductivity due to delocalization of π electrons in benzene rings. As a result, a 3.4 times enhancement of photocatalytic H2 generation was achieved from the g-C3N4 with benzene ring incorporation in comparing with that of pristine g-C3N4. More interestingly, H2 generation still occurs under irradiation of the light of λ ≥ 490 nm, above the absorption edge of pristine g-C3N4 (∼ 460 nm), illustrating the positive effectiveness of incorporated benzene rings on enhancing the H2 generation capacity of g-C3N4. The present work manifests the advantages of increasing π-conjugated electrons on designing highly active g-C3N4 photocatalysts.

Sub-5 nm monodispersed metal oxides have been attracting much attention in energy storage due to their large electrolyte ion-accessible surface areas and high specific capacities. However, the high surface free energy of ultrasmall nanoparticles inevitably results in their serious aggregation, leading to degraded electrochemical activities and poor cycling stability. Herein, a two-stage microimpinging stream reactor (TS-MISR) strategy that combines a first homogeneous premixing stage with a subsequent microimpinging stream reacting stage has been constructed for the controllable synthesis of Ni–Co–O/RGO composites (NCG). Benefiting from the enhanced micromixing efficiency and better process control of TS-MISR, monodispersed ultrasmall Ni–Co–O particles (3–4 nm) are evenly grown on the RGO flakes to generate a large specific surface area (293.2 m2 g−1), quantities of desirable mesopores (2–4 nm), as well as a strong synergistic effect between Ni–Co–O particles and conductive RGO flakes, hence providing more superficial electroactive sites, fast electron transfer and short diffusion paths for electrolyte ions to participate in faradaic redox reactions. The as-prepared NCG-MM exhibits a large specific capacity of 912.4 C g−1 (capacitance of 2281 F g−1) at the current density of 1 A g−1, good rate capability and cycling stability. Coupled with the activated carbon (AC) negative electrode, the assembled pouch-type NCG//AC asymmetric supercapacitor displays a prominent areal energy density (0.898 mW h cm−2 at 0.8 mW cm−2) and an excellent cycling stability (∼90.5% capacity retention after 8000 cycles). In addition, this strategy opens up an important prospect for the controllable synthesis of monodispersed metal oxide/graphene composites for application in batteries, sensors and catalysis.

To examine how two dominant species coexist within a tidal wetland in the Yellow River Delta, we studied the spatial distribution patterns and ecological relationships of Tamarix chinensis and Suaeda salsa. We also analyzed the relationship between these two plant species and soil chemical properties. Nine quadrats were established, and aerial photography was carried out in July 2018 in the study area to investigate plants and soil. Results showed that T. chinensis showed an aggregation distribution at scales of 0-10 m, 0-30 m, and 0-50 m from the sea to inland. Unlike T. chinensis, S. salsa showed an aggregation distribution at approximately 0-50 m in the study area, which meant the aggregation distributions of T. chinensis and S. salsa were found at different scales and S. salsa tended to aggregate distribution compared with T. chinensis. Meanwhile, T. chinensis and S. salsa had negative correlations far from the sea at a scale of 0-20 m and at the offshore area at a scale of 0-30 m. However, in the intermediate area, S. salsa and T. chinensis showed a positive correlation at a scale of 0-30 m. In general, the relationship between the two groups tends to be negatively correlated in a small range. Given that the tidal action decreased from the sea to inland, the driving factors of population aggregation gradually changed from tidal flooding to an interspecific relationship. The different characteristics of the different species may also have had an effect. And the aggregation of adult plant species had a beneficial impact on the establishment and growth of seedlings and plants. Furthermore, soil properties comprised complex actions including environmental conditions and ecological processes. The soil chemical properties such as soil salinity and nutrients were also influenced by the species' canopy.

BACKGROUND: Methyl levulinate (ML) is a promising green candidate for bio‐based diesel fuels and fuel additives. An effective method for synthesizing ML from levulinic acid (LA) catalyzed by cheap metal salt catalyst under mild conditions was developed. A series of metal salts were screened for the synthesis of ML from LA, and aluminum chloride was identified as a suitable catalyst for this process. RESULTS: The effects of catalyst loading, the molar ratio of methanol to LA, reaction temperature and reaction time on LA conversion and ML yield were investigated. The response surface method was used to optimize the process, and the model validation experiment showed that the predicted values corresponded well with the actual ones. Under the optimum conditions of reaction temperature 343 K, reaction time 1.5 h, aluminum chloride 1.14 g and molar ratio of methanol to LA 8:1, a high ML yield of 95.0 mol% could be obtained. Moreover, a kinetic model was proposed to evaluate the reaction process at a temperature range of 30–70 °C. The first‐order pseudo model was considered most suitable (R² > 0.99), and the activation energy of the reaction Eₐ was estimated to be 32.28 kJ mol⁻¹. Investigation of the reuse of the catalyst revealed that it retained good catalytic activity after repeated use for ten times. CONCLUSION: A green and efficient process of ML production from LA catalyzed by the metal salt aluminum chloride was developed. © 2020 Society of Chemical Industry

State-of-the-art molecular electronics focus on the measurement of electrical properties of materials at the single-molecule level. Experimentally, molecular electronics face two primary challenges. One challenge is the reliable construction of single-molecule junctions, and the second challenge is the arbitrary modulation of electron transport through these junctions. Over the past decades, electrochemistry has been widely adopted to meet these challenges, leading to a wealth of novel findings. This review starts from the application of electrochemical methods to the fabrication of nanogaps, which is an essential platform for the construction of single-molecule junctions. The utilization of electrochemistry for the modification of molecular junctions, including terminal groups and structural backbones, is introduced, and finally, recent progress in the electrochemical modulation of single-molecule electron transport is reviewed.

Crystalline metal-organic frameworks of divalent transition metal terephthalate belong to a new kind of high-capacity lithium storage materials. In this paper, CoCl 2 aqueous solution and CoCl 2 ·6H 2 O particles are comparatively used as starting materials to react with aqueous lithium terephthalate (Li 2 TP), resulting in the hierarchical architectures of dihydrate cobalt terephthalate (CoTP·2H 2 O No.1, No.2) by a solution-based π-π stacking self-assembly, respectively. Each of the two hydrated samples, as well as its well-crystallized anhydrous counterpart (CoTP No.1 or No.2), acquire a specific surface area no bigger than 4.5 m 2 g −1 but deliver a reversible capacity no less than 815.0 mAh g −1 at 200 mA g −1 in the 100th cycle. The decreasing order of lithium-storage capability (CoTP·2H 2 O No.1 2 O No.2 −1 , the 350th cycle) of CoTP No.2 structure and indicates a successful approach to the facile preparation of the organic anode material for high-performance lithium-ion batteries.

The ability to rationally design binder-free electrode materials that possess interconnected nanostructures is highly desirable for lithium-ion batteries (LIBs) with long cycling and excellent rate performances. Such electrode containing pores between nanostructures imparts large-area contact with electrolyte, improved electrical conductivity with current collector, and good structural stability and mechanical integrity. Herein, we report, for the first time, outstanding cycling stability and rate performance of CuO electrode in LIBs. CuO nano-labyrinths (NLs) composed of densely interlaced nanowalls on Cu foil are crafted via a facile solution-based etching process. It is notable that macroscopic and mesoscopic pores are found to ubiquitously present among the adjacent CuO nanowalls and within the nanowall, respectively (i.e., forming hierarchically porous CuO NLs). Intriguingly, CuO NLs anodes yield an ultralong cycling stability, that is, a specific capacity of 320 mA h g−1 after 800 cycles without the capacity fading at high current density of 1 A g−1, and an outstanding high-rate performance (up to 30 C). This is a direct consequence of unique synergistic effects of hierarchical pores and interlaced nanostructures. Moreover, a further enhancement of reversible capacity is achieved by deposition Si thin film on the surface of CuO NLs. Such interlaced nanowall-containing structures with hierarchical pores represent an important type of architectures that underpin the development of electrode materials for long cycle-life energy storage devices.

Wetland ecosystem, with their precious natural resources and important ecological functions, is an integral part of the global ecosystem. Preferential flow is a form of water and solute transport that is widely present in all types of soils and has a great impact on nutrient transport and environmental pollution in soils. In this paper, we observe the phenomenon of preferential flow within a wetland ecosystem and discuss the possible effects of preferential flow within a wetland on the wetland ecosystem as a background. We conducted dye tracing experiments outdoors. The preferential flow was qualitative analysis using soil composition. It was found that two types of preferential flow existed in the experimental area, namely finger flow and macropore flow. Quantitative analysis of the preferential flow was performed using PS and Image-Pro Plus software to obtain the intensity data of the preferential flow. The results show that the preferential flow phenomenon in the experimental area is obvious and the preferential-flow intensity data is high. We also found a clear correlation between initial soil–water content, which is an environmental factor characteristic of wetlands, and the preferential-flow data (p = 0.04

Though solar cells are one of the promising technologies to address the energy crisis, this technology is still far from commercialization. Thermoelectric materials offer a novel opportunity to convert energy between thermal and electrical aspects, which show the feasibility to improve the performance of solar cells via heat management and light harvesting. Polymer–inorganic thermoelectric nanocomposites consisting of inorganic nanomaterials and functional organic polymers represent one kind of advanced hybrid nanomaterials with tunable optical and electrical characteristics and fascinating interfacial and surface chemistry. During the past decades, they have attracted extensive research interest due to their diverse composition, easy synthesis, and large surface area. Such advanced nanomaterials not only inherit low thermal conductivity from polymers and high Seebeck coefficient, and high electrical conductivity from inorganic materials, but also benefit from the additional interface between each component. In this review, we provide an overview of interfacial chemistry engineering and electrical feature of various polymer–inorganic thermoelectric hybrid nanomaterials, including synthetic methods, properties, and applications in thermoelectric devices. In addition, the prospect and challenges of polymer–inorganic nanocomposites are discussed in the field of thermoelectric energy.

Graphene is a promising platform for configurable terahertz (THz) devices due to its reconfigurability, but most researches focus on its electrical tunability. Here, we propose a graphene-based THz metasurface comprised of graphene cut-wire arrays for magnetic manipulation of the THz wave. With the external magnetostatic field applied, the resonant currents of the graphene cut-wire can be effectively affected by the Lorentz force, leading to an evident tuning of the response of the metasurface. The simulated results fully demonstrate that the resonance frequencies of the graphene THz metasurface can be efficiently modulated under a vertical magnetostatic field bias, resulting in the manipulation of the transmittance and phase of the THz wave. As a new method of the tunable THz metasurface, our structure shows promising applications in the THz regime, including the ultracompact THz modulators and magnetic field sensors.

Coastal wetlands are ecologically and economically important; however, they are currently faced with fragmentation and loss. Plants are a fundamental element of wetlands and previous researches have focused on wetland plant connectivity; however, these researches have been conducted at the landscape but not species level. Here, given that tidal flats are important areas in coastal wetlands, we investigated the connectivity characteristics of typical plant species and environmental factors in different wetland regions influenced by various tidal conditions to reveal vegetation connectivity and its relationship with environmental factors on a small-patch scale. We found that tides negatively affect plant connectivity because both the Tamarix chinensis and Suaeda salsa have the highest connectivity on river banks, which are not influenced by tides. Of two tidal regions, different tides conditions have different influence on two plant species. T. chinensis had higher connectivity in the supratidal zone, whereas S. salsa had higher connectivity in the intertidal zone. Besides, the soil water content and soil salinity were significantly different in the three regions, but the soil total nitrogen and phosphorous were not. Soil water content and soil salinity were two factors that significantly affected plant connectivity. Specifically, soil water content positively affected the connectivity of T. chinensis and S. salsa, whereas soil salinity negatively affected the connectivity of T. chinensis. Taken together, these results indicate that tidal conditions affect plant connectivity on a small-patch scale. River banks and supratidal zone are beneficial for the recovery and growth of T. chinensis, intertidal zone and river banks are more conducive to the recovery and growth of S. salsa. Based on the above research, this study provides insights that could be applied to vegetation restoration in coastal wetlands.

Hierarchical TiO2-based hollow spheres were successfully synthesized via a hydrothermal method using FeSO4·7H2O, CoSO4·7H2O and ZnSO4·7H2O as soft templates. The as-prepared hollow spheres are well dispersed with the diameters of 2–4 μm. The shell and the interior surface of the spheres are composed of loosely packed grains, which provide a large specific surface area to facilitate lithium-ion diffusion processes. Among the three types of hybrid hollow spheres, TiO2/Fe2O3 shows the highest reversible capacity and best cycling stability (discharge capacities of 290.8 and 210.5 mAh/g were achieved after 100 cycles at 0.1C and 1C, respectively) and rate performance (from 461.1 mAh/g at 0.1C to 79.3 mAh/g at 5C with recovery to 288.6 mAh/g at 0.1C) for anode materials in lithium-ion batteries.

Summary Transition metal oxide catalysts with high oxygen reduction activity and durability are highly desirable for use in fuel cells and metal-air batteries. Herein we report, for the first time, the oxygen reduction activity of hollow porous spinel AB 2 O 4 microspheres, where A = Zn 2+ and B = Mn 3+ and/or Co 3+ (i.e., ZnMn x Co 2−x O 4 ). Among them, ZnMnCoO 4 ( x = 1) microspheres exhibit the best oxygen reduction activity with a half-wave-potential only 50 mV lower than that of the Pt/C counterpart and an excellent durability in the alkaline solution. Importantly, the electronic transition of Co 3+ ions from low-spin state in commercial Co 3 O 4 catalyst to a mixed high-spin and low-spin state in ZnMnCoO 4 catalyst was found to weaken the Co 3+ -OH bond and facilitate the O 2− /OH − displacement. The density functional theory calculation substantiated that ZnMnCoO 4 displayed a more favorable binding energy with O 2 and oxygenated species, thereby enabling the fast reaction kinetics in the oxygen reduction reaction process.

Co-axial silicon-coated carbon nanotubes (CNTs/Si) were successfully synthesized via a hydrothermal method. Sandwich-like carbon-coated CNTs/Si were obtained by an additional carbon coating. The as-prepared materials show superior cycling performance as anode materials in lithium ion batteries with a current density as high as 500 mA g−1 with no observable structural changes during the charge/discharge process. In addition, stable reversible discharge capacities as high as 1508.5 mA h g−1 after 1000 cycles were obtained. At higher current densities of 1 A g−1 and 2 A g−1, the CNTs/Si/C nanotubes also showed ideal cycling performance with reversible discharge capacities of 1216.6 mA h g−1 and 932.2 mA h g−1, respectively. The sandwich-like hollow tube structure of CNTs/Si/C not only alleviates the volume change during cycling, but also facilitates Li-ion and electron transport, and stabilizes the SEI layer. These results suggest that sandwich-like CNTs/Si/C nanotubes are a promising anode material for lithium ion batteries.

Apparently, plant leaf surface particulate matter (PM) can be effectively removed by rainfall, leaving space on the leaf surface to adsorb and retain PM again. At present, most of the relevant studies adopt the method of artificial rainfall simulation to quantify rainfall characteristics in terms of rainfall intensity, and mostly focus on one category of plants. Studies of rainfall intensity on different categories of plants are lacking. Therefore, in this study, common urban greenery plants were classified into four categories, namely, trees, shrubs, herbs, and aquatic plants. Artificial rainfall was used and three different gradients of rainfall intensity, 30 mm/h, 45 mm/h and 60 mm/h, were set. The mass of per unit leaf area PM removal was calculated using the elution weighing method and the filter membrane method was used to classify the PM into three particle sizes: coarse (10–100-μm), fine (3–10-μm) and ultrafine (0.4–3-μm). It was devoted to investigating the differences in the effect of rainfall intensity on the removal of PM from the leaf surfaces of different categories of common urban greenery. The results showed that the removal of coarse particles by rainfall was the highest under different rainfall intensities. At the same time, the removal effects of rainfall on leaf surface PM of herbs were the highest under different rainfall intensity, while that of trees was the lowest. Among the same category of plants, Salix matsudana had better particle retention capacity among trees, Buxus sinica among shrubs, Poa pratensis among herbs, and Acorus calamus among aquatic plants. In addition, all tested plants had the highest mass of PM removed from leaf surface units at high rainfall intensity (60 mm/h). However, at a higher rainfall intensity (45 mm/h), the mass of PM on plant unit leaf surface removed was lower than the minimum rainfall intensity (30 mm/h). The results of the above study can provide a basis and theoretical support for the selection of species for urban green space restoration, as well as a reference for the establishment of urban cleaning systems from the perspective of the relationship between rainfall intensity and PM on plant leaf surfaces.

Hollow SnO2 spheres with oriented cone-like SnO2 nanoparticle shells were synthesized by a one-step hydrothermal process using NaF as the morphology controlling agent. The resulting hollow SnO2 sphere electrode exhibits high reversible capacity (initial charge and discharge capacities of 1342.9 and 1947.6 mAh/g at 0.1 C and 1235.4 and 1741.3 mAh/g at 1 C) and good cycling stability (discharge capacities maintained 758.1 and 449.6 mAh/g after 100 cycles at 0.1 C and 1 C, respectively). Good rate performance was also obtained (1234.5 mAh/g at 0.1 C, 884.2 mAh/g at 0.2 C, 692.4 mAh/g at 0.5 C, 497.6 mAh/g at 1 C, 315.8 mAh/g at 2 C and 80.6 mAh/g at 5 C, and more importantly, when the current density returns to 0.1 C, a capacity of 869.6 mAh/g can be recovered. The observed electrochemical performance can attributed to the hollow structure, the use of NaF for morphology control and the unique oriented cone-like shell of the particles.

In this paper, a framework of macro-/micro-porous carbon derived from commercial lignin is prepared by one-step carbonization/activation method and then utilized as sulfur-loading matrix to assay the effect of sulfur-loading time on the structural and electrochemical properties of carbon-sulfur composite (C-S-t, t defined as sulfur-loading time). As-prepared porous carbon possesses a high specific surface area of 1211.6 m 2 g −1 and a pore volume of 0.59 cm 3 g −1 , acquires oxygen-containing functional groups on the surface of framework and functionalizes for the chemical adsorption of elemental sulfur. Under N 2 atmosphere (flow rate ∼ 60 mL min −1 ) the longer is the sulfur-loading time, the lower value is the total sulfur content of carbon-sulfur composite and the higher percentage of sulfur embedded within the micropores. At a sulfur-loading time of ∼10 h, the resulting C-S-10 composites have a total sulfur content as low as 50.0 wt% (44.8% in micropores) but exhibit the better electrochemical performances than C-S-6 composites formed at 6 h (sulfur ∼ 58.8 wt%, 29.4% in micropores). Therefore, aside from the structural properties of porous carbon, an optimized sulfur-loading time, as well as the chemical binding between carbon host and sulfur, should be considered to develop high-performance cathode materials for liquid electrolyte lithium-sulfur (Li-S) batteries.

Sodium manganese hexacyanoferrate (PBM) is one of the most promising cathode materials for sodium-ion batteries due to its high theoretical capacity, high voltage, and low cost. However, its cycling performance is limited by serious Mn ions dissolution during Na+ insertion/extraction. In this work, a facile in situ ion-exchange strategy is developed to synthesize sodium manganese hexacyanoferrate coated by sodium nickel hexacyanoferrate (PBM@PBN). The as-prepared PBM@PBN showed superior cyclic stability and enhanced rate capability. PBM@PBN exhibited a high reversible capacity of 126.9 mAh g−1 (1 C), with a capacity retention of 74.3% after 800 cycles. ICP results proved that superior cyclic stability was attributed to the inhibition of Mn ions dissolution by PBN coating. Besides, PBM@PBN also exhibited enhanced rate capability, and it delivered a high capacity of 87.2 mAh g−1 at 10 C. Ex-situ XRD proved that the PBM@PBN undergoes a reversible structural change (monoclinic ↔ cubic/tetragonal) during the whole cycle. PBN coating inhibited the PBM from suffering serious Mn ions dissolution during Na+ insertion/extraction, thus ensured the framework stability of PBM during long-term cycling and contributed to the excellent electrochemical performance. The simple preparation of PBM@PBN makes it accessible for large-scale applications.

The ability of photoanodes to simultaneously tailor light absorption, charge separation, and water oxidation processes represents an important endeavor toward highly efficient photoelectrochemical (PEC) water splitting. Here, a robust strategy is reported to render markedly improved PEC water splitting via sandwiching a photothermal Co3 O4 layer between a BiVO4 photoanode film and an FeOOH/NiOOH electrocatalyst sheet. The deposited Co3 O4 layer manifests compelling photothermal effect upon near-infrared irradiation and raises the temperature of the photoanodes in situ, leading to extended light absorption, enhanced charge transfer, and accelerated water oxidation kinetics simultaneously. The judiciously designed NiOOH/FeOOH/Co3 O4 /BiVO4 photoanode renders a superior photocurrent density of 6.34 mA cm-2 at 1.23 V versus a reversible reference electrode (VRHE ) with outstanding applied bias photon-to-current efficiency of 2.72% at 0.6 VRHE . In addition to the metal oxide, a wide variety of metal sulfides, nitrides, and phosphides (e.g., CoS, CoN, and CoP) can be exploited as the heaters to yield high-performance BiVO4 -based photoanodes. Apart from BiVO4 , other metal oxides (e.g., Fe2 O3 and TiO2 ) can also be covered by photothermal materials to impart significantly promoted water splitting. This simple yet general strategy provides a unique platform to capitalize on their photothermal characteristics to engineer high-performing energy conversion and storage materials and devices. National Research Foundation (NRF) This work was supported by the National Natural Science Foundation of China (51902297, 52002361, and 51903080), the Fundamental Research Funds for National Universities, China University of Geosciences (Wuhan), the Fund of the Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, and the Singapore National Research Foundation Investigatorship (NRF-NRFI2018-03).

Hydrological connectivity is an essential driver of the stability, structure, and function of wetland ecosystems. Small-scale hydrological connectivity restricts large-scale hydrological cycle processes. This study aimed to investigate the response of soil and root properties to hydrological connectivity at the soil profile scale. Tamarix chinensis, which is a typical plant of the Yellow River Delta wetland, was sampled for analysis. We investigated soil and root properties in the three study plots where T. chinensis distributed and compared them at different soil depths and under different hydrological connectivity conditions. We found that the soil organic carbon (SOC), soil organic matter (SOM), and soil total nitrogen (STN) were significantly higher in shallow soil (0–10 cm deep), and that root architecture parameters such as root length and width at soil depth of 0–10 cm were also significantly higher than at other soil depths. Both the soil nutrients and root architecture parameters were significantly influenced by hydrological connectivity. Specifically, SOC, SOM, and STN were significantly higher in regions of high hydrological connectivity than in regions of low hydrological connectivity. Additionally, root length, root surface area, root projected area, and root volume were markedly higher in regions of high hydrological connectivity. Furthermore, root length and width had significant positive correlations with both SOC and SOM in regions of high hydrological connectivity. Taken together, these results indicate that higher hydrological connectivity promotes soil nutrients and root architecture at the soil profile scale. In the process of wetland protection and restoration, we should not only pay attention to hydrological connectivity at a watershed scale, but also to improving hydrological connectivity at smaller scales so as to restore soil nutrients and promote plant growth.

Well-controlled nanostructures and a high fraction of Sn/Li2O interface are critical to enhance the coulombic efficiency and cyclic performance of SnO2-based electrodes for lithium-ion batteries (LIBs). Polydopamine (PDA)-coated SnO2 nanocrystals, composed of hundreds of PDA-coated “corn-like” SnO2 nanoparticles (diameter ca. 5 nm) decorated along a “cob”, addressed the irreversibility issue of SnO2-based electrodes. The PDA-coated SnO2 were crafted by capitalizing on rationally designed bottlebrush-like hydroxypropyl cellulose-graft-poly (acrylic acid) (HPC-g-PAA) as a template and was coated with PDA to construct a passivating solid-electrolyte interphase (SEI) layer. In combination, the corn-like nanostructure and the protective PDA coating contributed to a PDA-coated SnO2 electrode with excellent rate capability, superior long-term stability over 300 cycles, and high Sn→SnO2 reversibility.

Interconnected nickel bicarbonate (Ni(HCO3)2) hollow spheres were produced and exploited for the first time as an anode of lithium ion batteries, delivering the 80th reversible capacity of 1442 mAh g–1 at a current rate of 100 mA g–1, which is 3.9 times the theoretical capacity of commercial anode graphite. The time-dependent study suggested a self-sacrificial templating formation mechanism that yielded intriguing interconnected hollow structures. X-ray photoelectron spectroscopy measurements on cycled electrodes indicated that both the deep oxidation of Ni2+ into Ni3+ and the reversible reactions in HCO3– accounted for the ultrahigh capacity of Ni(HCO3)2 in comparison to its generally accepted theoretical capacity of 297 mAh g–1. Morphological characterizations revealed that the interconnected hollow structures enabled the enhanced rate performance and cycling stability, compared to those of the solid counterpart, because of their larger contact areas with electrolyte and better buffering effect to accom...

As a lithium-ion battery (LIB) anode, transition metal oxide nanostructures usually exhibit an initially decreasing and subsequently increasing trend of specific discharge capacity, owing to the gradually enhanced interfacial storage capability. In this paper, a novel base-catalyzed reaction of nickel acetate is used to synthesize flowerlike hollow architectures of basic carbonate based precursor and then to obtain NiO flowerlike porous hollow nanostructures with a high surface-to-volume ratio. As a LIB anode at 200 mA g −1 , the observed discharge capacity of the working electrode decreases from an initial value of 1584.7 mAh g −1 to the minimum value of 867.5 mAh g −1 in the 76th cycle and then increases to the maximum value of 2142.8 mAh g −1 in the 350th cycle. In each cycle, an interfacial fraction of the discharge capacity can be clearly distinguished and quantitatively estimated according to the discharging behaviors. These prove that the seemingly battery-to-pseudocapacitor transition relates both to bulk capacity loss and to interfacial capacity gain, depending upon the applied C-rate. Furthermore, the ordered arrangement of gradually crystallized Li 2 CO 3 , a main component of solid-electrolyte interface (SEI) layer, and its non-faradaic (double-layer capacitive) and faradaic (further reverse lithiation-delithiation) contributions may explain the over-compensating ability of interfacial storage.

In order to provide useful and effective reference indicators for wetland protection and restoration, we are trying to understand the role of hydrological processes in wetlands with hydrological connectivity. To quantify hydrological connectivity at soil-profile scale with the soil-profile indexes, dye-tracing field tests were conducted in Yellow River Delta to determine the size and distribution of soil pores, as well as the trail of waterflow. After data analyses, the results showed: (1) where preferential pathways were rich, that is, where hydrological connectivity was strong, the dye coverage was larger (the dye coverage of CLa1 was 0.20 ± 0.08, when CLa2 was 0.22 ± 0.05 and CLa3 was 0.13 ± 0.02), and the dye coverage of preferential pathway was larger (the dye coverage of preferential pathway of CLa1 was 0.16 ± 0.07, when CLa2 was 0.19 ± 0.04 and CLa3 was 0.11 ± 0.02). (2) hydrological connectivity weakens non-linearly from about 30 cm deep. (3) hydrological barrier in soil made dye coverage increase at 10–20 cm deep and it would weaken the vertical hydrological connectivity and strengthen the horizontal hydrological connectivity by preventing the flow from infiltrating further down.

Recent progress in addressing electrically driven single-molecule behaviors has opened up a path toward the controllable fabrication of molecular devices. Herein, the selective fabrication of single-molecule junctions is achieved by employing the external electric field. For molecular junctions with methylthio (-SMe), thioacetate (-SAc), amine (-NH2 ), and pyridyl (-PY), the evolution of their formation probabilities along with the electric field is extracted from the plateau analysis of individual single-molecule break junction traces. With the increase of the electric field, the SMe-anchored molecules show a different trend in the formation probability compared to the other molecular junctions, which is consistent with the density functional theory calculations. Furthermore, switching from an SMe-anchored junction to an SAc-anchored junction is realized by altering the electric field in a mixed solution. The results in this work provide a new approach to the controllable fabrication and modulation of single-molecule junctions and other bottom-up nanodevices at molecular scales.

Nickel-cobalt borides (denoted as NCBs) have been considered as a promising candidate for aqueous supercapacitors due to their high capacitive performances. However, most reported NCBs are amorphous that results in slow electron transfer and even structure collapse during cycling. In this work, a nanocrystallized NCBs-based supercapacitor is successfully designed via a facile and practical microimpinging stream reactor (MISR) technique, composed of a nanocrystallized NCB core to facilitate the charge transfer, and a tightly contacted Ni-Co borates/metaborates (NCBi ) shell which is helpful for OH- adsorption. These merits endow NCB@NCBi a large specific capacity of 966 C g-1 (capacitance of 2415 F g-1 ) at 1 A g-1 and good rate capability (633.2 C g-1 at 30 A g-1 ), as well as a very high energy density of 74.3 Wh kg-1 in an asymmetric supercapacitor device. More interestingly, it is found that a gradual in situ conversion of core NCBs to nanocrystallized Ni-Co (oxy)-hydroxides inwardly takes place during the cycles, which continuously offers large specific capacity due to more electron transfer in the redox reaction processes. Meanwhile, the electron deficient state of boron in metal-borates shells can make it easier to accept electrons and thus promote ionic conduction.

Commercial lithium-ion batteries (LIBs), limited by their insufficient reversible capacity, short cyclability, and high cost, are facing ever-growing requirements for further increases in power capability, energy density, lifespan, and flexibility. The presence of insulating and electrochemically inactive binders in commercial LIB electrodes causes uneven active material distribution and poor contact of these materials with substrates, reducing battery performance. Thus, nanostructured electrodes with binder-free designs are developed and have numerous advantages including large surface area, robust adhesion to substrates, high areal/specific capacity, fast electron/ion transfer, and free space for alleviating volume expansion, leading to superior battery performance. Herein, recent progress on different kinds of supporting matrixes including metals, carbonaceous materials, and polymers as well as other substrates for binder-free nanostructured electrodes in LIBs are summarized systematically. Furthermore, the potential applications of these binder-free nanostructured electrodes in practical full-cell-configuration LIBs, in particular fully flexible/stretchable LIBs, are outlined in detail. Finally, the future opportunities and challenges for such full-cell LIBs based on binder-free nanostructured electrodes are discussed.

Inorganic nanoparticles have become a research focus in numerous fields because of their unique properties that distinguish them from their bulk counterparts. Controlling the size and shape of nanoparticles is an essential aspect of nanoparticle synthesis. Preparing inorganic nanoparticles by using block copolymer templates is one of the most reliable routes for tuning the size and shape of nanoparticles with a high degree of precision. In this Review, we discuss recent progress in the design of block copolymer templates for crafting spherical inorganic nanoparticles including compact, hollow, and core-shell varieties. The templates are divided into two categories: micelles self-assembled from linear block copolymers and unimolecular star-shaped block copolymers. The precise control over the size and morphology of nanoparticles is highlighted as well as the useful properties and applications of such inorganic nanoparticles.

The vaporization process of gold film irradiated by ultrashort-pulsed laser is investigated using the parabolic two-step model and the dual-hyperbolic two-step model. The liquid–vapor interfacial velocity in the vaporization process is obtained by considering the interface energy balance equation and gas kinetics law. Comparisons between the temperature, velocity and location of the interface based on two different models are presented, the results show a great difference between them. In addition, the variation of ablation depth with pulse widths and fluence are also compared. The effects of laser parameters and film thickness on vaporization process are investigated. The relationship between the maximum temperature, velocity of liquid–vapor interface and laser fluence are also studied.

The cross-plane charge transport is demonstrated in single-molecule two-dimensional van der Waals heterojunctions., Two-dimensional van der Waals heterojunctions (2D-vdWHs) stacked from atomically thick 2D materials are predicted to be a diverse class of electronic materials with unique electronic properties. These properties can be further tuned by sandwiching monolayers of planar organic molecules between 2D materials to form molecular 2D-vdWHs (M-2D-vdWHs), in which electricity flows in a cross-plane way from one 2D layer to the other via a single molecular layer. Using a newly developed cross-plane break junction technique, combined with density functional theory calculations, we show that M-2D-vdWHs can be created and that cross-plane charge transport can be tuned by incorporating guest molecules. The M-2D-vdWHs exhibit distinct cross-plane charge transport signatures, which differ from those of molecules undergoing in-plane charge transport.