Self-Assembled Carbon Metal-Organic Framework Oxides Derived from Two Calcination Temperatures as Anode Material for Lithium-Ion Batteries

Owing to their structural diversity and mesoporous construction, metal-organic frameworks (MOFs) have been used as templates to prepare mesoporous metal oxides, which show excellent performance as anode materials for lithium-ion batteries (LIBs). Co-ZnO/C and Co-Co3O4/C nanohybrids were successfully synthesized based on a precursor of Co-doped MOF-5 by accurately controlling the annealing temperature and atmosphere. Experimental data proved that their electrochemical performance was closely associated with the material phase, especially for Co-ZnO/C, indicating that carbon skeleton materials can maintain a good restoration rate of over 99% after undergoing high-current density cycling. Meanwhile, Co-Co3O4/C nanohybrids showed an exceedingly high reversible capacity of 898 mAh∙g-1 at a current density of 0.1 C after 100 cycles. Their improved coulombic efficiency and superior rate capability contribute to a mesoporous structure, which provides pathways allowing for rapid Li+ diffusion and regulates volume change during charge and discharge processes.

A Review on the Application of Cobalt-Based Nanomaterials in Supercapacitors

Among many electrode materials, cobalt-based nanomaterials are widely used in supercapacitors because of their high natural abundance, good electrical conductivity, and high specific capacitance. However, there are still some difficulties to overcome, including poor structural stability and low power density. This paper summarizes the research progress of cobalt-based nanomaterials (cobalt oxide, cobalt hydroxide, cobalt-containing ternary metal oxides, etc.) as electrode materials for supercapacitors in recent years and discusses the preparation methods and properties of the materials. Notably, the focus of this paper is on the strategies to improve the electrochemical properties of these materials. We show that the performance of cobalt-based nanomaterials can be improved by designing their morphologies and, among the many morphologies, the mesoporous structure plays a major role. This is because mesoporous structures can mitigate volume changes and improve the performance of pseudo capacitance. This review is dedicated to the study of several cobalt-based nanomaterials in supercapacitors, and we hope that future scholars will make new breakthroughs in morphology design.

Reusable Co-nanoparticles for general and selective N-alkylation of amines and ammonia with alcohols

A general cobalt-catalyzed N-alkylation of amines with alcohols by borrowing hydrogen methodology to prepare different kinds of amines is reported. The optimal catalyst for this transformation is prepared by pyrolysis of a specific templated material, which is generated in situ by mixing cobalt salts, nitrogen ligands and colloidal silica, and subsequent removal of silica. Applying this novel Co-nanoparticle-based material, >100 primary, secondary, and tertiary amines including N-methylamines and selected drug molecules were conveniently prepared starting from inexpensive and easily accessible alcohols and amines or ammonia.

Synthesis and Electrochemical Properties of Bi2MoO6/Carbon Anode for Lithium-Ion Battery Application

High capacity electrode materials are the key for high energy density Li-ion batteries (LIB) to meet the requirement of the increased driving range of electric vehicles. Here we report the synthesis of a novel anode material, Bi2MoO6/palm-carbon composite, via a simple hydrothermal method. The composite shows higher reversible capacity and better cycling performance, compared to pure Bi2MoO6. In 0-3 V, a potential window of 100 mA/g current density, the LIB cells based on Bi2MoO6/palm-carbon composite show retention reversible capacity of 664 mAh·g-1 after 200 cycles. Electrochemical testing and ab initio density functional theory calculations are used to study the fundamental mechanism of Li ion incorporation into the materials. These studies confirm that Li ions incorporate into Bi2MoO6 via insertion to the interstitial sites in the MoO6-layer, and the presence of palm-carbon improves the electronic conductivity, and thus enhanced the performance of the composite materials.

Hollow nanoparticle-assembled hierarchical NiCo2O4 nanofibers with enhanced electrochemical performance for lithium-ion batteries

Hollow NiCo₂O₄ nanoparticle-assembled electrospun nanofibers showed tailorable electrochemical activity and tunable lithium storage properties.

Surfacing amorphous Ni-B nanoflakes on NiCo2O4 nanospheres as multifunctional bridges for promoting lithium storage behaviors

Transition metal oxides (TMOs) have gained enormous research interests as negative materials of next generation lithium-ion batteries due to their higher energy density, lower cost, and better eco-friendliness. However, they are prone to low electronic conductivities and dramatic volume change during charge/discharge and there is also a great challenge in realizing TMO electrodes with satisfactory LIB performances. In this study, for the first time, amorphous nickel-boride (Ni-B) was introduced into porous NiCo2O4 nanospheres by an in situ solution growth route to overcome the existing issues. The coated Ni-B component could not only function as anchors for NiCo2O4 nanospheres to suppress the severe volume expansion but could also act as effective electron-conducting bridges to promote fast electron/charge transfer. Furthermore, the existence of abundant mesopores centered at ∼6.5 nm in this composite could effectively suppress the severe volume variations in the lithiation/delithiation process. As expected, the NiCo2O4@Ni-B composites delivered a high reversible capacity of 1221 mA h g-1 at 0.2 A g-1 and 865 mA h g-1 at 0.5 A g-1 over 500 cycles; more impressively, at the high rate of 5 A g-1, a capacity of 648 mA h g-1 could be also obtained, showing its good rate capability. As a result, these results demonstrated an effective and facile way to design conversion-type negative electrode materials with superior lithium storage properties.

Mesoporous nickel cobalt manganese sulfide yolk–shell hollow spheres for high-performance electrochemical energy storage

Mesoporous Ni–Co–Mn sulfide yolk–shell hollow spheres have been prepared via a self-template route and show excellent electrochemical performance in supercapacitors.

The high efficient catalytic properties for thermal decomposition of ammonium perchlorate using mesoporous ZnCo2O4 rods synthesized by oxalate co-precipitation method

Mesoporous ZnCo₂O₄ rods have been successfully prepared via oxalate co-precipitation method without any template. The nano-sized spinel crystallites connected together to form mesoporous structure by annealing homogeneous complex oxalates precursor at a low rate of heating. It is found that the low anneal rate plays an important role for the formation of mesoporous ZnCo₂O₄ rods. The effects of the heat temperature on the phase, morphology and catalytic properties of the products were studied. The XRD, SEM TEM, and N₂ absorption/desorption have been done to obtain compositional and morphological information as well as BET surface area of the as-prepared sample. Catalytic activities of mesoporous ZnCo₂O₄ rods toward the thermal decomposition of ammonium perchlorate (AP) were investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The results show that the addition of ZnCo₂O₄ rods to AP dramatically reduces the decomposition temperature. The ZnCo₂O₄ rods annealed at 250 °C possesses much larger specific area and exhibits excellent catalytic activity (decrease the high decomposition temperature of AP by 162.2 °C). The obtained mesoporous ZnCo₂O₄ rods are promising as excellent catalyst for the thermal decomposition of AP.

Porous Hollow Superlattice NiMn2O4/NiCo2O4 Mesocrystals as a Highly Reversible Anode Material for Lithium-Ion Batteries

As a promising high-capacity anode material for Li-ion batteries, NiMn₂O₄ always suffers from the poor intrinsic conductivity and the architectural collapse originating from the volume expansion during cycle. Herein, a combined structure and architecture modulation is proposed to tackle concurrently the two handicaps, via a facile and well-controlled solvothermal approach to synthesize NiMn₂O₄/NiCo₂O₄ mesocrystals with superlattice structure and hollow multi-porous architecture. It is demonstrated that the obtained NiCo_1.5Mn_0.5O₄ sample is made up of a new mixed-phase NiMn₂O₄/NiCo₂O₄ compound system, with a high charge capacity of 532.2 mAh g⁻¹ with 90.4% capacity retention after 100 cycles at a current density of 1 A g⁻¹. The enhanced electrochemical performance can be attributed to the synergistic effects of the superlattice structure and the hollow multi-porous architecture of the NiMn₂O₄/NiCo₂O₄ compound. The superlattice structure can improve ionic conductivity to enhance charge transport kinetics of the bulk material, while the hollow multi-porous architecture can provide enough void spaces to alleviate the architectural change during cycling, and shorten the lithium ions diffusion and electron-transportation distances.

Performance enhancement of asymmetric supercapacitors with bud-like Cu-doped Mn3O4 hollow and porous structures on nickel foam as positive electrodes

Cu-doped Mn₃O₄ hollow nanostructures supported on Ni foams as high-performance electrode materials for supercapacitors were successfully synthesized through a facile hydrothermal method and subsequent calcination. The morphology, structure, and electrochemical performance of the as-prepared Mn₃O₄ nanostructures can be tuned just by varying the Cu doping content. Benefiting from the unique bud-like hollow structure, the 1.5 at% Cu-doped Mn₃O₄ sample has a high specific capacitance of 257.6 F g⁻¹ at 1 A g⁻¹ and remarkable stability (about 90.6% retention of its initial capacitance after 6000 electrochemical cycles). Besides, an asymmetric supercapacitor (ASC) cell based on the 1.5 at% Cu-doped Mn₃O₄ exhibits a high specific capacitance of 305.6 F g⁻¹ at 1 A g⁻¹ and an energy density of 108.6 W h kg⁻¹ at a power density of 799.9 W kg⁻¹. More importantly, the ASC shows good long-term stability with 86.9% capacity retention after charging/discharging for 6000 cycles at a high current density of 5 A g⁻¹.

The effect of Cu doping on the electrochemical performance of bud-like Mn₃O₄ nanostructures for supercapacitor application was comparatively investigated.

CoMnxOy nanosheets with molecular-scale homogeneity: an excellent catalyst for toluene combustion

The redox–precipitation technique yields molecularly dispersed CoMn_xO_y nanosheets with improved physicochemical properties compared to those obtained by a conventional co-precipitation method, leading to excellent catalytic activity in toluene combustion.

Morphology-Conserved Transformations of Metal-Based Precursors to Hierarchically Porous Micro-/Nanostructures for Electrochemical Energy Conversion and Storage

To meet future market demand, developing new structured materials for electrochemical energy conversion and storage systems is essential. Hierarchically porous micro-/nanostructures are favorable for designing such high-performance materials because of their unique features, including: i) the prevention of nanosized particle agglomeration and minimization of interfacial contact resistance, ii) more active sites and shorter ionic diffusion lengths because of their size compared with their large-size counterparts, iii) convenient electrolyte ingress and accommodation of large volume changes, and iv) enhanced light-scattering capability. Here, hierarchically porous micro-/nanostructures produced by morphology-conserved transformations of metal-based precursors are summarized, and their applications as electrodes and/or catalysts in rechargeable batteries, supercapacitors, and solar cells are discussed. Finally, research and development challenges relating to hierarchically porous micro-/nanostructures that must be overcome to increase their utilization in renewable energy applications are outlined.

Sacrificial Template Strategy toward a Hollow LiNi1/3Co1/3Mn1/3O2 Nanosphere Cathode for Advanced Lithium-Ion Batteries

In this work, a hollow LiNi_1/3Co_1/3Mn_1/3O₂ (H-NCM) nanosphere cathode with excellent electrochemical performance is developed for lithium-ion batteries. Preparation of the H-NCM nanospheres involves the sacrificial template method, in which carbon nanospheres work as the template and polyvinylpyrrolidone works as an additive. Structural and morphological analyses show that the as-prepared H-NCM nanospheres are highly uniform with diameters of approximately 50 nm and wall thicknesses of 10 nm. Electrochemical tests demonstrate that the H-NCM cathode not only manifests outstanding rate performance in the potential window of 2.5-4.5 V with high reversible specific capacities of 205.6, 194.9, 177.8, 165.9, 151.7, 126.0, and 115.3 mA h g^-1 at 0.1, 0.2, 0.5, 1, 2, 5, and 10 C, respectively, but also delivers excellent stability with a capacity retention of 60.1% at 10 C after 2000 cycles. The superior electrochemical performance of the H-NCM cathode can be put down to the distinctive hollow interior structure with thin nanostructured walls, which can synergistically benefit the significantly enhanced rate capability and cycling stability.

Self-Templated Synthesis of Porous Ni(OH)2 Nanocube and Its High Electrochemical Performance for Supercapacitor

Porous Ni(OH)₂ nanocubes were successfully fabricated by a simple self-sacrificial-template protocol using Ni-Co Prussian blue analogue (PBA) as precursor. When treated with NaOH, the simultaneous corrosion of Ni-Co PBA precursor and formation of amorphous Ni(OH)₂ resulted in porous Ni(OH)₂ nanocubes with uniform size of about 100 nm. Due to the large specific surface area and unique regular porous structure, the as-prepared materials showed large specific capacitance, relatively stable rate capability and long cycle stability when used as electrode materials for supercapacitors. With the voltage between 0.00 and 0.45 V versus Ag/AgCl, the specific capacitance can achieve 1842 F/g at a current density of 1 A/g.

A morphology, porosity and surface conductive layer optimized MnCo2O4 microsphere for compatible superior Li(+) ion/air rechargeable battery electrode materials

Uniform surface conductive layers with porous morphology-conserved MnCo2O4 microspheres are successfully synthesized, and their electrochemical performances are thoroughly investigated. It is found that the microwave-assisted hydrothermally grown MnCo2O4 using citric acid as the carbon source shows a maximum Li(+) ion lithiation/delithiation capacity of 501 mA h g(-1) at 500 mA g(-1) with stable capacity retention. Besides, the given microsphere compounds are effectively activated as air cathode catalysts in Li-O2 batteries with reduced charge overpotentials and improved cycling performance. We believe that such an affordable enhanced performance results from the appropriate quasi-hollow nature of MnCo2O4 microspheres, which can effectively mitigate the large volume change of electrodes during Li(+) migration and/or enhance the surface transport of the LiOx species in Li-air batteries. Thus, the rationally designed porous media for the improved Li(+) electrochemical reaction highlight the importance of the 3D macropores, the high specific area and uniformly overcoated conductive layer for the promising Li(+) redox reaction platforms.

Muti-component nanocomposite of nickel and manganese oxides with enhanced stability and catalytic performance for non-enzymatic glucose sensors

A muti-component nanocomposite of nickel and manganese oxides with a uniformly dispersed microspherical structure has been fabricated by a hydrothermal synthesis method. The as-prepared nanocomposite has been employed as a sensing material for non-enzymatic glucose detection and shown excellent electrocatalytic activity, such as high sensitivities of 82.44 μA mM(-1) cm(-2) and 27.92 μA mM(-1) cm(-2) over the linear range of 0.1-1 mM and 1-4.5 mM, respectively, a low detection limit of 0.2 μM and a fast response time of <3 s. Moreover, satisfactory specificity and excellent stability have also been achieved. The results demonstrate that a muti-component nanocomposite of nickel and manganese oxides has great potential applications as glucose sensors.

Controlled synthesis of CoxMn3−xO4 nanoparticles with a tunable composition and size for high performance lithium-ion batteries

Preparation of Co_xMn_3−xO₄ nanoparticles using bimetallic coordination-polymer precursors, and a case study of MnCo₂O₄ for LIBs, suggesting an optimal size for improved capacity retention.

One-pot synthesis of monodispersed porous CoFe2O4 nanospheres on graphene as an efficient electrocatalyst for oxygen reduction and evolution reactions

Monodispersed porous CoFe₂O₄ nanospheres grown on graphene with high ORR/OER activities are fabricated by a simple one-pot solvothermal method.

A simple synthesis of hollow Mn2O3 core–shell microspheres and their application in lithium ion batteries

Hollow Mn₂O₃ core–shell microspheres were successfully fabricated via a mixed method including a solution method and a subsequent thermal decomposition.

Glucose sensing and low-threshold field emission from MnCo2O4 nanosheets

Manganese cobalt oxide (MnCo₂O₄) nanosheets were grown on Nickel (Ni) foam by a simple electrodeposition method and its glucose sensing and field emission properties have been investigated.

The design and synthesis of porous NiCo2O4 ellipsoids supported by flexile carbon nanotubes with enhanced lithium-storage properties for lithium-ion batteries

The as-prepared 3D porous NiCo₂O₄ ellipsoids supported by flexile carbon nanotubes nanowire arrays show high reversible capacity, excellent cycling stability, and good rate capability when used as an anode material for LIBs.

An overview of AB2O4- and A2BO4-structured negative electrodes for advanced Li-ion batteries

Energy-storage devices are state-of-the-art devices with many potential technical and domestic applications.

Porous mixed metal oxides: design, formation mechanism, and application in lithium-ion batteries

The relentless pursuit of new electrode materials for lithium ion batteries (LIBs) has been conducted for decades. Structures with either porous or nanostructure configurations have been confirmed as advantageous candidates for energy storage/conversion applications. The integration of the two features into one structure can provide another chance to improve the electroactivities. Recently, single-phased mixed metal oxides (MMOs) containing different metal cations, in particular, have confirmed high electrochemical activities because of their complex chemical composition, interfacial effects, and the synergic effects of the multiple metal species. In this review, we will focus on recent research advances of MMOs with porous architectures as anode materials in the matter of structural arrangement and compositional manipulation. Moreover, the application of self-supported MMO-based porous structures as LIB anodes is also explained herein. More importantly, investigations on the synthetic system and formation mechanism of porous MMOs will be highlighted. Some future trends for the innovative design of new electrode materials are also discussed in this review. The challenges and prospects will draw many researchers' attention.

Heterostructured core-shell ZnMn₂O₄ nanosheets@carbon nanotubes' coaxial nanocables: a competitive anode towards high-performance Li-ion batteries

In this study, we rationally designed a rapid, low-temperature yet general synthetic methodology for the first time, involving in situ growth of two-dimensional (2D) birnessite-type MnO2 nanosheets (NSs) upon each carbon nanotube (CNT), and we designed the subsequent phase transformation into untrathin mesoporous ZnMn2O4 NSs with a thickness of ∼2-3 nm at room temperature to efficiently fabricate heterostructured core-shell ZnMn2O4 NSs@CNT coaxial nanocables with well-dispersed and tunable ZnMn2O4 loading. The underlying insights into the low-temperature formation mechanism of the unique core-shell hybrid nanoarchitectures were tentatively proposed here. When utilized as a high-performance anode for advanced LIBs, the resultant core-shell ZnMn2O4@CNTs' coaxial nanocables (∼84.5 wt.% loading) exhibited large specific discharge capacity (∼1033 mAh g(-1)), good rate capability (∼528 mAh g(-1)) and excellent cycling stability (average capacity degradation of only ∼5.2% per cycle) at a high current rate of 1224 mA g(-1), originating from the distinct core-shell synergetic effect of fast electronic delivery and from the large electrode/electrolyte contacting surfaces/interfaces provided by three-dimensional entangling coaxial CNT-based nanonetwork topology.

PSA modified 3 D flower-like NiCo2O4 nanorod clusters as anode materials for lithium ion batteries

3 D flower-like NiCo₂O₄ nanorod clusters as anode materials for lithium ion batteries exhibit excellent electrochemical performance.

Influence of the synergistic effect between Co–N–C and ceria on the catalytic performance for selective oxidation of ethylbenzene

A series of catalysts, i.e. metal oxides (MO) such as CeO₂, Fe₂O₃ and Al₂O₃ supported Co–N–C (Co–N–C/MO) were prepared by heating supported cobalt porphyrin in a N₂ atmosphere.

Pristine hollow microspheres of Mn2O3 as a potential anode for lithium-ion batteries

Ascorbic acid aided inside-out Ostwald ripening promotes the formation of Mn₂O₃ microspheres with a hollow interior surface that exhibits an appreciable capacity of 610 mA h g⁻¹, even after completing 100 cycles.

Nanoflake driven Mn2O3 microcubes modified with cooked rice derived carbon for improved electrochemical behavior

Mn₂O₃ microcubes, symmetrically formed out of the systematic stacking of nanoflakes, built with nanoparticles in the 30–50 nm range have been obtained from a simple co-precipitation method.

A highly moisture-resistant Fe-doped mesoporous Co3O4 catalyst for efficient low-temperature CO oxidation

Compared with pure Co₃O₄ spinel, the Fe-doped catalyst demonstrates high catalytic activity and stability in low temperature CO oxidation under moisture conditions.