Formation of N-Doped Carbon-Coated ZnO/ZnCo2 O4 /CuCo2 O4 Derived from a Polymetallic Metal-Organic Framework: Toward High-Rate and Long-Cycle-Life Lithium Storage

Fabricating ZnO@C composites based on Nypa fruticants shell-derived cellulose for high performance lithium-ion battery anodes

In this study, Nypa fruticans shell-derived cellulose was successfully produced, and the hydrothermal method was employed to generate ZnO@C (ZOC) composites, which were then subjected to calcination in N2 gas at a temperature of 600 °C for varying durations. X-ray diffraction and thermogravimetric analyses demonstrated that the annealing duration had a substantial impact on the quantities of C and ZnO in the ZOC composites. The scanning electron microscope images indicated the presence of ZnO nanoparticles on the surface of the C phase and revealed a similar morphology among the ZOC composites. ZOC anodes exhibited excellent electrochemical properties when used in lithium-ion batteries (LIBs), making them promising alternatives to graphite as LIB anode materials. As an illustration, the ZOC_2h electrode delivered a reversible capacity of 500 mAh g-1 after 100 cycles at a current density of 0.1 A g-1. The excellent electrochemical performance of the ZOC electrodes may be attributed to the carbon matrix obtained from cellulose, the appropriate quantity of C and ZnO phases in the ZOC composites, and their distinctive structure.

Unveiling the scope and perspectives of MOF-derived materials for cutting-edge applications

Although synthesis and design of MOFs are crucial factors to the successful implementation of targeted applications, there is still lack of knowledge among researchers about the synthesis of MOFs and their derived composites for practical applications. For example, many researchers manipulate study results, and it has become quite difficult to quit this habit specifically among the young researchers Undoubtedly, MOFs have become an excellent class of compounds but there are many challenges associated with their improvement to attain diverse applications. It has been noted that MOF-derived materials have gained considerable interest owing to their unique chemical properties. These compounds have exhibited excellent potential in various sectors such as energy, catalysis, sensing and environmental applications. It is worth mentioning that most of the researchers rely on commercially available MOFs for use as precursor supports, but it is an unethical and wrong practice because it prevents the exploration of the hidden diversity of similar materials. The reported studies have significant gaps and flaws, they do not have enough details about the exact parameters used for the synthesis of MOFs and their derived materials. For example, many young researchers claim that MOF-based materials cannot be synthesized as per the reported instructions for large-scale implementation. In this regard, current article provides a comprehensive review of the most recent advancements in the design of MOF-derived materials. The methodologies and applications have been evaluated together with their advantages and drawbacks. Additionally, this review suggests important precautions and solutions to overcome the drawbacks associated with their preparation. Applications of MOF-derived materials in the fields of energy, catalysis, sensing and environment have been discussed. No doubt, these materials have become excellent class but there are still many challenges ahead to specify it for the targeted applications.

Boosting the high-rate performance of lithium-ion battery anodes using MnCo2O4/Co3O4 nanocomposite interfaces

Herein, a mesoporous MnCo2O4/Co3O4 nanocomposite was fabricated using a polyvinylpyrrolidone (PVP)-assisted hydrothermal synthesis method by maintaining only the non-stoichiometric ratio of Mn and Co (2 : 6), leading to an extra phase of Co3O4 coupled with MnCo2O4. Microstructural analysis showed that the obtained sample has a uniform nanowire-like morphology composed of interconnected nanoparticles. The stoichiometric ratio (2 : 4) was maintained to synthesize pure MnCo2O4 for comparative analysis. However, the obtained structure of pure MnCo2O4 was found to be irregular and fragile. After their employment as anode-active materials, the nanocomposite electrode showed superior high rate capability (1043.8 mA h g-1 at 5C) and long-term cycling stability (773.6 mA h g-1 after 500 cycles at 0.5C) in comparison to the pure MnCo2O4 electrode (771.5 mA h g-1 at 5C and 638.9 mA h g-1 at 0.5C after 500 cycles). It was believed that the extra phase of Co3O4 may also participate in the electrochemical reactions due to its high electrochemically active nature. Benefiting from the appealing architectural features and striking synergistic effect, the integrated MnCo2O4/Co3O4 nanocomposite anode exhibits excellent electrochemical properties and high cycle stability for LIBs.

Metal-organic-framework derived Zn-V-based oxide with charge storage mechanism as high-performance anode material to enhance lithium and sodium storage

Transition metal oxides have been extensively studied due to their large theoretical capacities, but their practical application has been hampered by low electrical conductivity and dramatic volume fluctuation during cycling. In this work, we synthesized Zn3V2O8 material using Zn-V-MOF (metal-organic framework) as a sacrificial template to improve the electrochemical characteristics of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Unique dodecahedral structure, larger specific surface area and higher ability to mitigate volume changes, improve the electrochemical reaction active site while accelerating ion transport. Zn3V2O8 with 2-methylimidazole as a ligand demonstrated a discharge capacity of 1225.9 mAh/g in LIBs and 761.6 mAh/g in SIBs after 300 cycles at 0.2 C. Density functional theory (DFT) calculation illustrates the smaller diffusion barrier energy and higher specific capacity in LIBs that is ascribed to the fact that Li has a smaller size and hence its diffusion is easier. This study may lead to a path for the manufacturing of high-performance LIBs and SIBs.

Hybrid Sub-1 nm Nanosheets of Co-assembled MnZnCuOx and Polyoxometalate Clusters as Anodes for Li-ion Batteries

Transition metal oxide (TMO) anode materials in lithium-ion batteries (LIBs) usually suffer from serious volume expansion leading to the pulverization of structures, further giving rise to lower specific capacity and worse cycling stability. Herein, by introducing polyoxometalate (POM) clusters into TMOs and precisely controlling the amount of POMs, the MnZnCuOx -phosphomolybdic acid hybrid sub-1 nm nanosheets (MZC-PMA HSNSs) anode is successfully fabricated, where the special electron rich structure of POMs is conducive to accelerating the migration of lithium ions on the anode to obtain higher specific capacity, and the non-covalent interactions between POMs and TMOs make the HSNSs possess excellent structural and chemical stability, thus exhibiting outstanding electrochemical performance in LIBs, achieving a high reversible capacity (1157 mAh g-1 at 100 mA g-1 ) and an admirable long-term cycling stability at low and high current densities.

Nanostructured conversion-type anode materials of metal-organic framework-derived spinel XMn2O4 (X = Zn, Co, Cu, Ni) to boost lithium storage

Bimetallic spinel transition metal oxides play a major part in actualizing eco-friendly electrochemical energy storage systems (ESSs). However, structural precariousness and low electrochemical capacitance restrict their actual implementation in lithium-ion batteries (LIBs). To address these demerits, the sacrificial template approach has been considered as a prospective way to strengthen electrochemical stability and rate performance. Herein, metal-organic frameworks (MOFs) derived XMn₂O₄-BDC (H₂BDC = 1,4-dicarboxybenzene, X = Zn, Co, Cu, Ni) are prepared by a hydrothermal approach in order to discover the effects of various metal cations on the electrochemical performance. Among them, ZnMn₂O₄-BDC displays best electrochemical properties (1321.5 mAh g^-1 at the current density of 0.1 A g^-1 after 300 cycles) and high efficiency with accelerated Li⁺ diffusivity. Density functional theory (DFT) calculations confirm the ZnMn₂O₄ possesses the weakest adsorption energy on Li⁺ with a minimized value of -0.92 eV. In comparison with other XMn₂O₄ through traditional fabrication method, MOF-derived XMn₂O₄-BDC possesses a higher number of Li⁺ transport channels and better electric conductivity. This tactic provides a feasible and effective method for preparing bimetallic transition metal oxides and enhances energy storage applications.

Metal-organic frameworks and their derivatives as electrode materials for Li-ion batteries: a mini review

In recent decades, in order to obtain more excellent performance and wider application of rechargeable lithium-ion batteries (LIBs), researchers have been exploring potential electrode materials. MOFs possess attractive features, such...

A facile synthesis of Ni0.85Se@Cu2-xSe nanorods as high-performance supercapacitor electrode materials

Transition-metal selenides are regarded as promising electrode materials due to their superior electrochemical performances for supercapacitors. In this study, a nanorod-like hybrid of Ni_0.85Se@Cu_2-xSe on a Ni-foam substrate is successfully synthesized via a facile one-step route. The Ni_0.85Se@Cu_2-xSe nanorods are found to be deposited uniformly on the Ni-form substrates. When used as a battery-type electrode in a supercapacitor, the as-deposited Ni_0.85Se@Cu_2-xSe electrode exhibits a high specific capacity of 1831 F g^-1 at 1 A g^-1 and 78.4% of capacitance retention after 8000 cycles at 10 A g^-1. Moreover, the assembled Ni_0.85Se@Cu_2-xSe//AC asymmetric supercapacitor (ASC) exhibits an energy density of 63.2 W h kg^-1 at a power density of 800.1 W kg^-1, as well as good cycling stability (92.1% capacitance retention after 5000 cycles).

Nanocomposite synthesis strategies based on the transformation of well-tailored metal-organic frameworks

Increasing the complexity of nanomaterials in terms of their structure and chemical composition has attracted significant attention, because it can yield unique scientific outcomes and considerable improvements for practical applications. Various approaches are being developed for the synthesis of nanostructured composites. Coordination polymers (CPs) emerged as new precursors in solid-state reactions for nanomaterials nearly two decades ago; the repetitively arranged inorganic and organic units can facilitate the production of nanoscale particles and porous carbon upon thermal decomposition. Metal-organic frameworks (MOFs), a subgroup of CPs featuring crystalline and porous structures, have subsequently become primary objects of interest in this field, as can be seen by the rapidly increasing number of reports on this topic. However, unique composite materials with increasingly complex nanostructures, which cannot be achieved via conventional methods, have been rarely realised, even though conventional MOF research has enabled the delicate control of structures at the molecular level and extensive applications as templates. In this regard, a comprehensive review of the fabrication strategies of MOF-based precursors and the thermal transformation into functional nanomaterials is provided herein, with a particular emphasis on the recent developments in nanocomposite research. We briefly introduce the roles and capabilities of MOFs in the synthesis of nanomaterials and subsequently discuss diverse synthetic routes for obtaining morphologically or compositionally advanced composite nanomaterials, based on our understanding of the MOF conversion mechanism.

Ionic-liquid assisted architecture of amorphous nanoporous zinc-rich carbon-based microstars for lithium storage

Amorphous Zn-rich nitrogen-doped carbon-based microstars are synthesized using an ionic liquid-assisted method and annealing process. The microstars exhibit a high reversible capacity of 756 mA h g-1 and a capacity retention of 98% after 120 cycles at 0.5 A g-1 due to their large surface area, hierarchical nanopores, and uniform distribution of zinc and nitrogen.

ZnO encapsulants: Design and new view

ZnO encapsulants with capsular configurations (e.g. a large inner cavity, sizeable pore, low density and high specific surface area) have attracted considerable attention as effective and promising candidates in various fields owing to the merits of ZnO (e.g. UV protection, photoelectric catalysis, gas sensitivity, antibacterial effect). However, the research on ZnO encapsulants has not yet reached the eruptive stage. This probably due to their high morphological flexibility and relatively low structural strength that is not easy to control during the preparation process. In this review, the principles of cavity-generating and pore-forming are firstly discussed in depth after going through the synthesis of hollow ZnO in the past ten years. Moreover, the regulation of cavity diameter and pore size of different synthetic strategies is investigated. Then, the research progress of ZnO encapsulants is debated in detail from the loading and release of functional materials and the corresponding characterization. Finally, some potential designs and new views on the future research and development of ZnO encapsulants are concluded.

Mo-Doped SnO2 Nanoparticles Embedded in Ultrathin Graphite Nanosheets as a High-Reversible-Capacity, Superior-Rate, and Long-Cycle-Life Anode Material for Lithium-Ion Batteries

A new ternary Mo-SnO₂-graphite composite has been constructed via hydrothermal and ball milling. The Mo/SnO₂ hybrids were homogeneously dispersed in graphite nanosheets. In the Mo-SnO₂-graphite, Mo can inhibit the Sn nanoparticle aggregation, enhance the reversible conversion reaction in lithiation, and improve the electrochemical performance. Consequently, the Mo-SnO₂-graphite composite contributes a high capacity of 1317.4 mAh g^-1 at 0.2 A g^-1 after 200 cycles, remarkable rate property of 514.0 mAh g^-1 at 5 A g^-1, and long-term cyclic stabilization of 759.0 mAh g^-1 after 950 cycles at 1.0 A g^-1. With outstanding electrochemical performance and facial synthesis, the ternary Mo-SnO₂-graphite is a hopeful anode material for lithium-ion batteries (LIBs).

Efficient Laser-Induced Construction of Oxygen-Vacancy Abundant Nano-ZnCo2 O4 /Porous Reduced Graphene Oxide Hybrids toward Exceptional Capacitive Lithium Storage

Recently, binary ZnCo₂ O₄ has drawn enormous attention for lithium-ion batteries (LIBs) as attractive anode owing to its large theoretical capacity and good environmental benignity. However, the modest electrical conductivity and serious volumetric effect/particle agglomeration over cycling hinder its extensive applications. To address the concerns, herein, a rapid laser-irradiation methodology is firstly devised toward efficient synthesis of oxygen-vacancy abundant nano-ZnCo₂ O₄ /porous reduced graphene oxide (rGO) hybrids as anodes for LIBs. The synergistic contributions from nano-dimensional ZnCo₂ O₄ with rich oxygen vacancies and flexible rGO guarantee abundant active sites, fast electron/ion transport, and robust structural stability, and inhibit the agglomeration of nanoscale ZnCo₂ O₄ , favoring for superb electrochemical lithium-storage performance. More encouragingly, the optimal L-ZCO@rGO-30 anode exhibits a large reversible capacity of ≈1053 mAh g^-1 at 0.05 A g^-1 , excellent cycling stability (≈746 mAh g^-1 at 1.0 A g^-1 after 250 cycles), and preeminent rate capability (≈686 mAh g^-1 at 3.2 A g^-1 ). Further kinetic analysis corroborates that the capacitive-controlled process dominates the involved electrochemical reactions of hybrid anodes. More significantly, this rational design holds the promise of being extended for smart fabrication of other oxygen-vacancy abundant metal oxide/porous rGO hybrids toward advanced LIBs and beyond.

Spinel Zinc Cobalt Oxide (ZnCo2O4) Porous Nanorods as a Cathode Material for Highly Durable Li-CO2 Batteries

Li-CO₂ batteries are of great interest among researchers due to their high energy density and utilization of the greenhouse gas CO₂ to produce energy. However, several shortcomings have been encountered in the practical applications of Li-CO₂ batteries, among which their poor cyclability and high charge overpotential necessary to decompose the highly insulating discharge product (Li₂CO₃) are the most important. Herein, the spinel zinc cobalt oxide porous nanorods with carbon nanotubes (ZnCo₂O₄@CNTs) composite is employed as a cathode material in Li-CO₂ batteries to improve the latter's cycling performance. The ZnCo₂O₄@CNT cathode-based Li-CO₂ battery exhibited a full discharge capacity of 4275 mAh g^-1 and excellent cycling performance over 200 cycles with a charge overpotential below 4.3 V when operated at a current density of 100 mA g^-1 and fixed capacity of 500 mAh g^-1. The superior performance of the ZnCo₂O₄@CNT cathode composite was attributed to the synergistic effects of ZnCo₂O₄ and CNT. The highly porous ZnCo₂O₄ nanorod structures in the ZnCo₂O₄@CNT catalyst showed enhanced catalytic activity/stability, which effectively promoted CO₂ diffusion during the discharging process and accelerated Li₂CO₃ decomposition at a low charge overpotential.

Pseudocapacitance-dominated high-performance and stable lithium-ion batteries from MOF-derived spinel ZnCo2O4/ZnO/C heterostructure anode

Spinel ZnCo₂O₄/ZnO/C hierarchically porous structures were successfully synthesized by two-step annealing of cyanide-bridged coordination polymer precursors.

Designing of Pb(II)-Based Novel Coordination Polymers (CPs): Structural Elucidation and Optoelectronic Application

[Pb₂(bdc)_1.5(aiz)] _n (1) and [Pb₂(bdc)_1.5(aiz)(MeOH)₂] _n (2) (H₂bdc = 1,4-benzene dicarboxylic acid, aiz = (E)-N'-(thiophen-2-ylmethylene)isonicotinohydrazide) have been synthesized, and structural characterization has been established by X-ray analysis and thermogravimetric analysis (TGA). Here, bdc^2- links two Pb(II) centers and the aiz ligand binds the metal centers in two different manners: chelating and monodonating. Thus, polymerizations have taken place from the combination of mixed ligand system. Optical band gaps have been studied via UV measurements. Again, the experimental and calculated (from density functional theory (DFT)) band gaps agree well and the semiconducting properties of synthesized polymeric materials have been approved. Thus, optoelectronic and photonic devices can be made by this type of coordination polymers (CPs). The I-V representative curves of 1 (device-A) and 2 (device-B) in both dark and illuminated conditions show that device-A has a higher magnitude of current than device-B. Dark- and photo-conductivity values of device-A are calculated as 2.94 × 10^-6 and 6.12 × 10^-6 S m^-1, respectively, whereas for device-B, the values of dark- and photo-conductivity are 2.92 × 10^-7 and 3.66 × 10^-7 S m^-1, respectively, at room temperature.

Graphene/Glycerin Solution-Based Multifunctional Stretchable Strain Sensor with Ultra-High Stretchability, Stability, and Sensitivity

Highly stretchable, flexible, and sensitive strain sensors have promising applications in motion detection-especially multifunctional strain sensors that can detect stretching, bending, compression and twisting. Herein, this study presents a graphene and glycerol solution-based multifunctional sensor with ultra-high stretchability and sensitivity. Owing to the self-lubrication and fluidity of the graphene-glycerol solution, the strain sensors display super stretchability up to 1000%, a maximum gauge factor up to 45.13, and excellent durability for over 10,000 cycles. In addition, the sensor can also rapidly respond to small strains (1%, 5%, 10%) and different stretching rates (12.5%/s, 25%/s, 50%/s, and 100%/s). More impressively, the sensors can measure up to 50 kPa pressure and 180° twisting without any damage. Furthermore, the strain sensors demonstrate their applicability in scenarios involving motion detection, such as that for finger bending, wrist rotating, touching, and drinking water.