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A robust solvothermal-driven solid-to-solid transition strategy is developed to craft tartaric acid-capped ultrafine SnO2 encapsulated in graphene with outstanding lithium and sodium storage reversibility due to effectively inhibited Sn coarsening.

Nano-polycrystalline Sn2S3/Sn3S4/FeS/Fe7S8 sulfides anchored on graphene were synthesized via annealing SnS2 and Fe followed by homogeneously combining them with exfoliated graphite.

Perfect absorption is realized by an anapole metamaterial composed only of oxide ceramics. The tolerance limits of metamaterial devices to an extreme environment, especially in a high-temperature oxidation environment, are being broken.

The tunneling current through the single-molecule junctions principally offers the ultimate solution for chemical and biochemical sensing via the interactions between probes and target analytes at the single-molecule level. However, it remains unexplored to achieve the sensitive and selective detection of targeted analytes using single-molecule junction techniques due to the challenge in quantitative evaluation of sensing sensitivity and selectivity. Herein, we demonstrate a single-molecule tunneling sensor for the highly sensitive and selective detection of nitrobenzene explosives using scanning tunneling microscope break junction (STM-BJ). Taking advantage of π-π stacking interactions between the molecular probes and nitrobenzene explosives, we use a spectral clustering algorithm to assign the signal of probes and π-stacked probes for sensitively detecting the targeted analytes and the distinguishable conductance change of probes when interacting with different nitroaromatic explosive compounds for selective detection. We find that pronounced conductance changes up to 0.8 orders of magnitude when the probes interact with TNT. Also, we obtain a sensitivity of up to ∼10 pM for TNT and high sensitivity for eight TNT analogues. Combined with theoretical calculations, we discover that the harness of the destructive quantum interference of the probe M1OH after interacting with TNT leads to high selectivity in sensing with TNT. Our work demonstrates the great potential of the single-molecule tunneling current for environmental sensing molecules with high selectivity and sensitivity.

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

The Yellow River Delta wetlands in the Yellow River Delta National Nature Reserve are facing serious degradation due to water scarcity and soil salinization. This study aims to investigate the mechanism of wetland degradation by analyzing the small-scale distribution of soil nutrients and preferential flow transport patterns in the Robinia Pseudoacacia community, which is a typical vegetation community in degraded wetlands. Soil physical and chemical properties based on field staining experiments were analyzed, and indoor solute penetration experiments were conducted to investigate the distribution of soil nutrients and hydrological characteristics. The results showed that the contents of soil organic carbon, organic matter, total nitrogen, and available phosphorus decreased with increasing soil depth, with higher contents in the preferential flow area than in the matrix flow area. Soil organic carbon, organic matter, total nitrogen, total phosphorus, and available phosphorus showed positive correlations with each other, while soil pH and conductivity exhibited negative correlations with the above nutrients. The efflux rate of the Acacia community exhibited a gradual decline as soil depth increased, and the relative concentration of the solution exhibited a non-monotonic pattern of decrease, increase, and subsequent decrease with increasing soil depth. The findings could provide valuable guidance for the restoration and management of degraded wetlands in the Yellow River Delta.

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.

In recent years, scholars have paid increased attention to the ecological role of crab burrows, particularly their impact on the hydrological processes of saltmarsh wetlands. This study aims to investigate the influence of crab burrows on soil water and salt transport and to understand the ecological significance of crab burrows in coastal wetlands from the perspective of ecohydrological processes. We combined a field sample survey and an indoor soil column infiltration experiment to analyze the differences in infiltration time, soil water content, and soil electrical conductivity (EC) between different experimental groups. Consequently, the results showed that the size of crab burrow diameter varies significantly in different areas of the coastal wetland, influenced by tidal creek and sea-land distances, with larger burrow diameters in areas around 5 m from the tidal creek. Large-diameter burrows (2.5 cm × 6) are more conducive to salt transport due to their preferential water conductivity to the underlying soil vertically, small-diameter burrows (0.5 cm × 6) could promote water infiltration uniformly and maintain good soil water retention capacity. This study's results provide insights into the hydrological connectivity and spatial distribution of salinity in coastal wetlands. Additionally, the positive impact of burrows on the water-salt environment of coastal wetland sediments may also provide new ideas for coastal wetland restoration.

The host-guest interaction acts as an essential part of supramolecular chemistry, which can be applied in confined reaction. However, it is challenging to obtain the dynamic process during confined reactions below micromolar concentrations. In this work, a new method is provided to characterize the dimerization process of the guest 1,2-bis(4-pyridinyl) ethylene in host cucurbit[8]curil using scanning tunneling microscope-break junction (STM-BJ) technique. The guest reaction kinetics is quantitatively by nuclear magnetic resonance (NMR) and in situ single-molecule junctions. It is found that in the single-molecule conductance measurements, the electrical signals of the reactants with a concentration as low as 5 × 10-6 m are clearly detected, and the reaction kinetics at micromolar concentrations are further obtained. However, in NMR measurements, the characteristic peak signal of the reactants is undetectable when the concentration of the reactants is lower than 0.5 × 10-3 m and it cannot be quantified. In addition, the strong electric field from the nanogap accelerates the reaction. This work reveals that single-molecule STM-BJ techniques are more sensitive for tracking confined reactions than that by NMR techniques and can be used to study effect of extremely strong electric field on kinetics.

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.

Growing populations and industrialization have led to increased nitrogen (N) loads in wetland ecosystems. A micro-constructed wetland planted with Lythrum salicaria L. to treat artificial wastewater was used to investigate the short-term variations in the plant biomass and dynamics of total nitrogen (TN) content. Our results showed that the biomass of Lythrum salicaria L. rapidly increased during the experiment due to their extensive root system and vigorous spread, and waterlogged conditions had little effect on the relationship between biomass and the TN content in soil and effluent. Under different waterlogged conditions, the TN removal rates in the water were all greater than 60%, providing a reference for the waterlogged conditions used in wetland eutrophication restoration.

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).

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.

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.

A series of metal-modified phosphotungstates were prepared and performed for direct synthesis of ethyl levulinate from fructose in ethanol. Considering the cost of catalysts, catalytic activity of catalysts, and easy separation of catalysts together, K-HPW-1 was chosen as the most suitable catalyst for synthesis of ethyl levulinate from fructose. A high ethyl levulinate yield of 64.6 mol% was obtained at 150 °C within 2 h in ethanol. The introduction of low polar toluene as a co-solvent improved the yield of ethyl levulinate to 68.7 mol%. The recovered catalyst remained high activity with the yield of ethyl levulinate converted from fructose above 50 mol% after being used five times. Moreover, the generality of the catalyst was further demonstrated by glucose, sucrose, inulin, and cellulose with ethyl levulinate yielding 14.5, 35.4, 52.3, and 14.8 mol%, respectively.

Synthesis of materials with desirable nanostructures is a hot research topic owing to their enhanced performances in contrast to the bulk counterparts. Herein, dumbbell-shaped cobalt carbonate (CoCO 3 ) nano architectures and the bulk counterpart of CoCO 3 rhombohedra are prepared via a facile hydrothermal route in the presence and absence of ascorbic acid (AA), respectively. By comparison, it has been found that: the addition of AA in the hydrothermal crystallization system changes the shape of the building blocks from Co 2 CO 3 (OH) 2 nanosheets to CoCO 3 nanoparticles, and then further influences the final configuration of the products. When applied as anodes of lithium ion batteries, CoCO 3 dumbbells deliver a 100th capacity of 1042 mAh g −1 at 200 mA g −1 and even exhibit a long-term value of 824 mAh g −1 over 500 cycles at 1000 mA g −1 , which are much higher than the rhombohedral counterparts with corresponding 540 and 481 mAh g −1 respectively. The much higher capacity, better cycling stability and enhanced rate performance of CoCO 3 dumbbells can be attributed to the higher specific surface area, smaller charge transport resistance and better structure stability resulting from the slight doping (∼4.6 wt%) of AA, and also relate with a novel lithium storage mechanism in CoCO 3 .

Porous AMn2O4 (A = Zn, Zn0.5Co0.5, Co) microspheres have been prepared through a carbonate co-precipitation and subsequent heat treatment at 600 °C. X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images reveal that, the porous AMn2O4 microspheres with hausmannite (Mn3O4) structure are composed of well-defined primary nanoparticles, and these nanoparticles have the size of 30–100 nm. As lithium-ion battery anodes, the electrochemical properties of porous AMn2O4 microspheres are determined by their chemical compositions. The porous ZnMn2O4 microspheres can retain a discharge capacity of 698.8 mAh g− 1 after 50 charge–discharge cycles, which is much better than the other two oxides. The CoMn2O4 shows the highest discharge potential among three samples. Interestingly, the Zn0.5Co0.5Mn2O4 inherits the shortage of CoMn2O4 and ZnMn2O4, and its cycling stability is the worst.