Construction of Binder-Free, Self-Supported, Hetero-Core-Shell Honeycomb Structured CuCo2 O4 @Ni0.5 Co0.5 (OH)2 with Abundant Mesopores and High Conductivity for High-Performance Energy Storage.

Clever and rational design of structural hierarchy, along with precise component adjustment, holds profound significance for the construction of high-performance supercapacitor electrode materials. In this study, a binder-free self-supported CCO@N0.5 C0.5 OH/NF cathode material is constructed with hierarchical hetero-core-shell honeycomb nanostructure by first growing CuCo2 O4 (CCO) nanopin arrays uniformly on highly conductive nickel foam (NF) substrate, and then anchoring Ni0.5 Co0.5 (OH)2 (N0.5 C0.5 OH) bimetallic hydroxide nanosheet arrays on the CCO nanopin arrays by adjusting the molar ratio of Ni(OH)2 and Co(OH)2 . The constructed CCO@N0.5 C0.5 OH/NF electrode material showcases a wealth of multivalent metal ions and mesopores, along with good electrical conductivity, excellent electrochemical reaction rates, and robust long-term performance (capacitance retention rate of 87.2%). The CCO@N0.5 C0.5 OH/NF electrode, benefiting from the hierarchical structure of the material and the exceptional synergy between multiple components, demonstrates an excellent specific capacitance (2553.6 F g-1 at 1 A g-1 ). Furthermore, the assembled asymmetric CCO@N0.5 C0.5 OH/NF//AC/NF supercapacitor demonstrates a high energy density (70.1 Wh kg-1 at 850 W kg-1 ), and maintains robust capacitance cycling stability performance (83.7%) after undergoing 10 000 successive charges and discharges. It is noteworthy that the assembled supercapacitor exhibits an operating voltage (1.7 V) that is well above the theoretical value (1.5 V).

Metal-Organic Frameworks and Their Derivatives-Based Nanostructure with Different Dimensionalities for Supercapacitors.

With the urgent demand for the achievement of carbon neutrality, novel nanomaterials, and environmentally friendly nanotechnologies are constantly being explored and continue to drive the sustainable development of energy storage and conversion installations. Among various candidate materials, metal-organic frameworks (MOFs) and their derivatives with unique nanostructures have attracted increasing attention and intensive investigation for the construction of next generation electrode materials, benefitting from their unique intrinsic characteristics such as large specific surface area, high porosity, and chemical tunability as well as the interconnected channels. Nevertheless, the poor electrochemical conductivity severely limits their application prospects, hence a variety of nanocomposites with multifarious structures have been designed and proposed from different dimensionalities. In this review, recent advances based on MOFs and their derivatives in different dimensionalities ranging from 1D nanopowders to 2D nanofilms and 3D aerogels, as well as 4D self-supporting electrodes for supercapacitors are summarized and highlighted. Furthermore, the key challenges and perspectives of MOFs and their derivatives-based materials for the practical and sustainable electrochemical energy conversion and storage applications are also briefly discussed, which may be served as a guideline for the design of next-generation electrode materials from different dimensionalities.

In Situ Synthesis of CoCeSx Bimetallic Sulfide Nanoparticles on a Bi-Pyrene Terminated Molecular Wire Modified Graphene Surface for Supercapacitors.

The excellent electrical conductivity of graphene is due to its highly-conjugated structures. Manipulation of the electronic and mechanical properties of graphene can be achieved by controlling the destruction of its in-sheet conjugation system. Herein, we report the preparation of CoCeSx -SA@BPMW@RGO through π-π stacking interactions at the molecular level. In this study, sodium alginate was reacted with Co2+ and Ce3+ , and the composite was loaded onto a graphene surface. The graphene sheets were prepared using a bi-pyrene terminated molecular wire (BPMW) to avoid re-stacking of the grapheme sheets, thereby forming nanoscale spaces between sheets. The angle between the BPMW coplanar pyrene group and the phenyl group was 33.2°, and the graphene layer is supported in an oblique direction. Finally, a three-dimensional porous composite was obtained after annealing and vulcanization. The obtained CoCeSx -SA@BPMW@RGO exhibited excellent electrical conductivity and remarkable cycle stability. When the current density was 1 A g-1 , its specific capacitance was as high as 1004 F g-1 . BPMW modifies graphene through the synergistic effect of π-π stacking interaction and special structure to obtain excellent electrochemical performance. Moreover, a solid-state asymmetric supercapacitor device was fabricated based on the synthesized CoCeSx -SA@BPMW@RGO hybrid, which exhibited a power density of 979 W kg-1 at an energy density of 23.96 Wh kg-1 .

MXene-Based Nanocomposites for Energy Conversion and Storage Applications.

Novel nanomaterials and advanced nanotechnology continuously push forward the rapid development of sustainable energy conversion and storage equipment. An emerging family of two-dimensional transition-metal carbides, nitrides and carbonitrides, also known as MXenes, have attracted increasing attention and in depth investigation. Benefitting from their unique intrinsic properties, MXenes have attracted significant attention and they have been considered as promising candidate materials for the development of environmentally friendly energy resources. A large number of studies show that MXenes have great potential in energy conversion and storage fields. Despite of their exceptional properties, MXenes also have some inherent characteristics, such as low capacities and unstable retention performances, which severely hinder their prospect applications in energy conversion and storage fields. In this Minireview, the latest progress on MXenes and their hybrid composites with small molecules, polymers, carbon or metal ions, and their applications in energy conversion and storage fields is highlighted, including their use in different types of batteries, supercapacitors, hydrogen/oxygen evolution reactions, electromagnetic interference absorption/shielding and solar steam generation. In addition, the critical challenges and further development prospects of MXene-based materials are also introduced.

Hollow 3D Frame Structure Modified with NiCo2 S4 Nanosheets and Spinous Fe2 O3 Nanowires as Electrode Materials for High-Performance All-Solid-State Asymmetric Supercapacitors.

Supercapacitors have attracted tremendous research interest, since they are expected to achieve battery-level energy density, while having a long calendar life and short charging time. Herein, a novel asymmetric supercapacitor has been successfully assembled from NiCo2 S4 nanosheets and spinous Fe2 O3 nanowire modified hollow melamine foam decorated with polypyrrole as positive and negative electrodes, respectively. Owing to the well-designed nanostructure and suitable matching of electrode materials, the assembled asymmetric supercapacitor (ASC) exhibits an extended operation voltage window of 1.6 V with an energy density of 20.1 Wh kg-1 at a power density of 159.4 kW kg-1 . Moreover, the ASC shows stable cycling stability, with 81.3 % retention after 4000 cycles and a low internal resistance of 1.03 Ω. Additionally, a 2.5 V light-emitting diode indicator can be lit up by three ASCs connected in series; this provides evidence of the practical application potential of the assembled energy-storage system. The excellent electrochemical performances should be credited to the significant enhancement of the specific surface area, charge transport, and mechanical stability resulting from the unique 3D morphology.

Fabrication of Cobaltosic Oxide Nanoparticle-Doped 3 D MXene/Graphene Hybrid Porous Aerogels for All-Solid-State Supercapacitors.

MXenes are a new family of 2 D transition metal carbides and nitrides, which have attracted enormous attention in electrochemical energy storage, sensing technology, and catalysis owing to their good conductivity, high specific surface area, and excellent electrochemical properties. In this work, a series of Co3 O4 -doped 3 D MXene/RGO hybrid porous aerogels is designed and prepared through a facile in situ reduction and thermal annealing process, in which the reduced graphene oxide (RGO) conductive network can electrically link the separated Co3 O4 -MXene composite nanosheets, leading to enhanced electronic conductivity. It is found that upon using the Co3 O4 -MXene/RGO hybrid porous aerogel prepared with a mass ratio of Co3 O4 -MXene/RGO of 3:1 (CMR31) as an electrode for a supercapacitor, a superior specific capacitance of 345 F g-1 at the current density of 1 A g-1 is achieved, which is significantly higher than those of Ti3 C2 Tx MXene, RGO, and MXene/RGO electrodes. In addition, a high capacitance retention (85 % of the initial capacitance after 10 000 cycles at a high current density of 3 A g-1 ) and a low internal resistance Rs (0.44 Ω) can be achieved. An all-solid-state asymmetric supercapacitor (ASC) device is assembled using CMR31, and it has the ability to light up a blue LED indicator for 5 min if four ASCs are connected in series. Therefore, these novel Co3 O4 -MXene/RGO hybrid porous aerogels have potential practical applications in high-energy storage devices.

Recent Advances in Functional Polymer Decorated Two-Dimensional Transition-Metal Dichalcogenides Nanomaterials for Chemo-Photothermal Therapy.

Novel nanomaterials and advanced nanotechnologies continue to promote the fast development of new approaches for efficient tumor therapy. As an alternative choice to various traditional therapies, non-invasive photothermal therapy (PTT) has attracted significant attention mainly due to its low cost, highly localizing, specific tumor treatment and minimal side effects on healthy tissues. PTT induced by photo-absorbing agents which can absorb and convert the external NIR laser into heat to ablate tumors. Plenty of studies have shown the significant potential of PTT to treat tumors in future practical applications. However, PTT alone usually could not eradicate tumors considering the intensity of laser gradual attenuates in biological tissues and the heat generated tends to distribute inhomogeneous within tumors tissues. Combination of chemotherapy with photothermal therapy into one system for tumor therapy is an effective strategy to further improve the therapy efficiency. In this Minireview, we focus on the recent advances in constructing PTT therapeutic and multi-model combination therapeutic via integrating nanomaterials and functional polymers.

A Target-Directed Chemo-Photothermal System Based on Transferrin and Copolymer-Modified MoS2 Nanoplates with pH-Activated Drug Release.

Molybdenum disulfide (MoS2 ) nanosheets have attracted significant attention due to their photothermal properties, but the poor solubility and colloidal stability limited their further application in biomedical field. Here, we report a targeted photothermal controllable nanocarrier consisting of MoS2 nanosheets modified with block copolymer P(OEG-A)-b-P(VBA-co-KH570) and targeting ligand transferrin. P(OEG-A)-b-P(VBA-co-KH570) is synthesized by RAFT polymerization and utilized not only to improve the solubility of MoS2 nanosheets but also efficiently load the anti-cancer drug doxorubicin (DOX) through an acid-cleavable Schiff base linker. Thiol-functionalized transferrin (Tf-SH) is anchored onto the surface of MoS2 nanosheets by the formation of disulfide bonds, which could further enhance the cellular uptake of DOX and MoS2 to HepG2 cells for high-efficiency synergetic therapy. The drug release experiments exhibited the minimal release of DOX at room temperature and neutral pH, and the maximal drug release of 53 % at acidic tumor pH and hyperthermia condition after 48 h. In addition, the DOX-loaded, Tf-SH and P(OEG-A)-b-P(VBA-co-KH570) modified MoS2 (DOX-POVK-MoS2 -Tf) showed better a therapeutic effect than DOX-POVK-MoS2 and POVK-MoS2 , probably owing to the combined effects of target-directed uptake, acid-triggered drug release, and NIR induced localized heating, which suggest the designed MoS2 nanocarriers are promising for applications in multi-modal cancer therapy.

Embedding of conductive Ag nanoparticles among honeycomb-like NiMn layered double hydroxide nanosheet arrays for ultra-high performance flexible supercapacitors.

Layered double hydroxides are considered promising electrode materials for the preparation of high-energy-density supercapacitors owing to their suitable microstructure and significant electrochemical properties. In this study, honeycomb-like NiMn-layered double-hydroxide (NiMn-LDH) nanosheet arrays with numerous electron/ion channels, a large number of active sites, considerable redox reversibility, and significant electrical conductivity were synthesized by combining Co2(OH)2CO3 nanoneedle arrays with NiMn-LDH nanosheet arrays and Ag nanoparticles on a carbon cloth (CC) substrate through a hydrothermal strategy (CC@Co2CH/NM-LDH-Ag). The fabricated CC@Co2CH/NM-LDH-Ag binder-free electrode exhibited a high specific capacitance of 10,976 mF cm-2 (3092F/g, 1391.4C g-1) at 2 mA cm-2 (1 A/g), and a high capacitance retention of 93.2 % after 10,000 cycles at a current density of 20 mA cm-2. In addition, a solid-state asymmetric supercapacitor (ASC) device assembled using CC@Co2CH/NM-LDH-Ag as the cathode possessed an ultrahigh energy density of 68.85 Wh kg-1 at a power density of 722.6 W kg-1, and two fabricated ASC units in series were able to power a multifunctional display for more than 30 min. Therefore, this study provides a new approach for the design and synthesis of high-performance flexible electrodes.

In Situ Generation of Vertically Crossed P-Cu3Se2 Ultrathin Nanosheets Derived from Cu2S Nanorod Arrays for High-Performance Supercapacitors.

Transition-metal selenides (TMSs) have great potential in the synthesis of supercapacitor electrode materials due to their rich content and high specific capacity. However, the aggregation phenomenon of TMS materials in the process of charging and discharging will cause capacity attenuation, which seriously affects the service life and practical applications. Therefore, it is of great practical significance to design simple and efficient synthesis strategies to overcome these shortcomings. Hence, P-doped Cu3Se2 nanosheets are loaded on vertically aligned Cu2S nanorod arrays to synthesize CF/Cu2S@Cu3Se2/P nanocomposites with a unique core-shell heterostructure. Notably, the Cu2S precursors can be rapidly converted into Cu3Se2 nanorod arrays in situ in just 30 min at room temperature. The unique core-shell heterostructure effectively avoids the aggregation phenomenon, and the doped P elements further enhance the electrochemical properties of the electrode materials. Therefore, the as-prepared CF/Cu2S@Cu3Se2/P electrode exhibits a high areal capacitance of 5054 mF cm-2 (1099 C g-1) at 3 mA cm-2 and still retains 90.2% capacitance after 10 000 galvanostatic charge-discharge (GCD) cycles. The asymmetric supercapacitor (ASC) device assembled from synthetic CF/Cu2S@Cu3Se2/P and activated carbon (AC) possesses an energy density of 41.1 Wh kg-1 at a power density of 480.4 W kg-1. This work shows that the designed CF/Cu2S@Cu3Se2/P electrode has broad application prospects in the field of electrochemical energy storage.

Ternary NiCeCo-Layered Double Hydroxides Grown on CuBr2@ZIF-67 Nanowire Arrays for High-Performance Supercapacitors.

Ternary layered double-hydroxide-based active compounds are regarded as ideal electrode materials for supercapacitors because of their unique structural characteristics and excellent electrochemical properties. Herein, an NiCeCo-layered double hydroxide with a core-shell structure grown on copper bromide nanowire arrays (CuBr2@NCC-LDH/CF) has been synthesized through a hydrothermal strategy and calcination process and utilized to fabricate a binder-free electrode. Due to the unique top-tangled structure and the complex assembly of different active components, the prepared hierarchical CuBr2@NCC-LDH/CF binder-free electrode exhibits an outstanding electrochemical performance, including a remarkable areal capacitance of 5460 mF cm-2 at 2 mA cm-2 and a capacitance retention of 88% at 50 mA cm-2 as well as a low internal resistance of 0.163 Ω. Moreover, an all-solid-state asymmetric supercapacitor (ASC) installed with CuBr2@NCC-LDH/CF and activated carbon electrodes shows a high energy density of 118 Wh kg-1 at a power density of 1013 W kg-1. Three assembled ASCs connected in series can operate a multifunctional display for over three and a half hours. Therefore, this innovative work provides new inspiration for the preparation of electrode materials for supercapacitors.

Controllable synthesis of nickel doped hierarchical zinc MOF with tunable morphologies for enhanced supercapability.

Metal-organic frameworks (MOFs) are attracting tremendous research interest because of their rich redox sites and high specific area which are beneficial for the energy storage applications. Nevertheless, the poor conductivity, low mechanical strength and unsatisfactory capacity severely hinder their wide application. Hence, it is of practical significance to design highly efficient and facile strategy to solve these issues. Herein, vertically oriented ZnO nanorod arrays are applied as precursor to synthesize laminated scale-like and highly-oriented Ni/Zn-MOF/ZnO nanocomposite. Owing to the desirable conductivity resulting from the doping nickel ions and the interaction between ZnO and its relative MOF, the fabricated 0.3Ni/Zn-MOF/ZnO@CC electrode exhibits an electrochemical capacitance of 1693 mF cm-2 at 1 mA cm-2. Moreover, the electrochemical capacitance retention of 80.7 % after 2500 cycling numbers is obtained under the constant current density of 10 mA cm-2 and the low internal resistance Rs of 0.89 Ω is observed. For practical application, the as-synthesized laminated scale-like Ni/Zn-MOF/ZnO@CC nanocomposite is served as positive electrode to fabricate solid-state asymmetric supercapacitor device. Moreover, a 2.5 V indicator could be powered for 8 min when the prepared supercapacitor units are connected. This work demonstrates the promising potential of the synthesized scale-like Ni/Zn-MOF composites for electrochemical energy storage applications.

Origami and layered-shaped ZnNiFe-LDH synthesized on Cu(OH)2 nanorods array to enhance the energy storage capability.

The combination of layered nanorod arrays with unique core-shell structure and transition metal layered double hydroxide (LDH) is considered as a feasible solution to improve the electrochemical performances of capacitor electrode. In this study, layered ZnNiFe-LDH@Cu(OH)2/CF core-shell nanorod arrays, which consist of ultrathin ZnNiFe-LDHs nanosheet shells and ordered Cu(OH)2 nanorod inner cores, are successfully designed and fabricated by a typical hydrothermal way and a simple in situ oxidation reaction. The electrode prepared using ZnNiFe-LDH@Cu(OH)2/CF nanomaterial reveals an remarkable area capacitance of 6100 mF cm-2 at 3 mA cm-2 current density, which is excellently superior than those of ZnFe-LDH@Cu(OH)2/CF, NiFe-LDH@Cu(OH)2/CF, Cu(OH)2/CF and CF. Additionally, the capacitance retention remains as high as 83.4% after 5000 cycles and a very small Rs (0.567 Ω) can be observed. In addition, an asymmetric supercapacitor device is successfully fabricated employing ZnNiFe-LDH@Cu(OH)2/CF. Meanwhile, the ZnNiFe-LDH@Cu(OH)2/CF//AC device can achieve an energy density of 44 Wh kg-1 and a corresponding power density of 720 W kg-1 and possess the capability to light up a multi-function monitor for 33 min just using two ASC equipments connected in series. Therefore, the prepared ZnNiFe-LDH@Cu(OH)2/CF composite materials with unique structure has great application potential in energy storage devices.

Ultrafast generation of highly crystalline graphene quantum dots from graphite paper via laser writing.

Graphene quantum dots (GQDs) are attractive fluorescent nanoparticles that have wide applicability, are inexpensive, nontoxic, photostable, water-dispersible, biocompatible and environmental-friendly. Various strategies for the synthesis of GQDs have been reported. However, simple and efficient methods of producing GQDs with control over the size of the GQDs, and hence their optical properties, are sorely needed. Herein, an ultra-fast and efficient laser writing technique is presented as a means to produce GQDs with homogeneous size from graphene produced by the instantaneous photothermal gasification and recrystallization mechanism. Controlling the laser scan speed and output power, the yield of GQDs can reach to be about 31.458 mg/s, which shows promising potential for large-scale production. The entire process eliminates the need for chemical solvents or any other reagents. Notably, the prepared laser writing produced GQDs (LWP-GQDs) exhibit blue fluorescence under UV irradiation of 365 nm and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates is measured at (0.1721, 0.123). Overall, this method exhibits superior advantages over the complex procedures and low yields required by other existing methods, and thus has great potential for the commercial applications.

Fabrication of Cobaltous Sulfide Nanoparticle-Modified 3D MXene/Carbon Foam Hybrid Aerogels for All-Solid-State Supercapacitors.

MXene is a neoteric type of bidimensional (2D) transition metal carbide/nitride with broad application prospects, in particular with electrochemical energy storage. The electrochemical performance of MXene is unsatisfactory because it is easy to stack resulting in the difficulty of electrolyte penetration and ion transport. In this study, the cobaltous sulfide-modified 3D MXene/N-doped carbon foam (CoS@MXene/CF) hybrid aerogel is projected and manufactured via simple in situ growth and thermal annealing strategies. The capacitance of the as-fabricated 300-CMC-31:1 electrode material reaches 250 F g-1 (1 A g-1), which is obviously higher than those of MXene, CoS@CF, 400-CMC-31:1, 300-CMC-10:1, 300-CMC-50:1, CF, and MXene/CF electrode materials. Moreover, it can hold 97.5% of the original capacitance after 10,000 cycles and the internal resistance (Rs) is only 0.50 Ω. A green bulb can be lit by two all-solid asymmetric supercapacitors installed in series. The prepared CoS@MXene/CF hybrid aerogel exhibits promising potential for practical application in energy storage areas.

A molecularly imprinted nanoreactor with spatially confined effect fabricated with nano-caged cascaded enzymatic system for specific detection of monosaccharides.

Glucose oxidase (GOx), traditionally regarded as an oxidoreductase with high ß-D-glucose specificity, has been widely applied as sensing probe for ß-D-glucose detection. However, it is found that the specificity of GOx is not absolute and GOx cannot decern ß-D-glucose among its isomers such as xylose, mannose and galactose. The existence of the other monosaccharides in sensing system could compromise the sensitivity for ß-D-glucose, therefore, it is of great urgency to achieve the highly specific catalytic performance of GOx. Herein, porous metal-organic frameworks (MOF) are prepared as the host matrix for immobilization of both GOx and bovine hemoglobin (BHb), obtained a cascaded catalytic system (MOF@GOx@BHb) with both enhanced GOx activity and peroxidase-like activity owing to the spatially confined effect. Then, using ß-D-glucose as both template molecules and substances, hydroxyl radicals are produced continuously and applied for initiating the polymerization of molecular imprinting polymers (MIPs) on the surface of MOF@GOx@BHb. Impressively, the obtaining molecularly imprinted GOx (noted as MOF@GOx@BHb-MIPs) achieves the highly sensitive and specific detection of ß-D-glucose in the concentration range of 0.5-20 µM with the LOD = 0.4 µM (S/N = 3) by colorimetry. Similarly, MOF@GOx@BHb-MIPs are subsequently obtained using mannose, xylose and galactose as template molecules, respectively, and also show satisfied specific catalytic activity towards corresponding templates, indicating the effectiveness of the proposed strategy to achieve highly specific catalytic performance of GOx.

In Situ Fabrication of a Uniform Co-MOF Shell Coordinated with CoNiO2 to Enhance the Energy Storage Capability of NiCo-LDH via Vapor-Phase Growth.

NiCo-layered double hydroxide (LDH) has attracted increasing attention in recent years for application in supercapacitors (SCs) owing to its high redox activity and intercalating capability. However, the pristine NiCo-LDH is unable to reach theoretical specific capacitance and satisfying rate capability due to the limited electroactive species and a low ion diffusion rate. Here, we demonstrate novel vertically aligned nanosheet arrays of cobalt metal-organic framework (Co-MOF)@CoNiO2 core-shell composites constructed by the in situ grown Co-MOF shell with a uniform and controlled thickness on the CoNiO2 core via a vapor-phase approach. Owing to the intimate contact and synergistic effect between the Co-MOF shell and the CoNiO2 core, the as-synthesized Co-MOF@CoNiO2 displays a high specific capacitance of about 571 F g-1, which is significantly higher than the pristine NiCo-LDH electrode (380 F g-1). Moreover, the capacitive properties of Co-MOF@CoNiO2 can be further boosted to 757.2 F g-1 after cyclic voltammetry oxidation. The easy preparation and high electrochemical performance of the Co-MOF@CoNiO2 composite make it a potential material for SC application. These findings may inspire the exploration and construction of other MOF shell coating metal oxide from various nanostructured LDHs for varied applications. In addition, the as-assembled EO-Co-MOF@CoNiO2/carbon cloth (CC)//activated carbon (AC) device can achieve a high capacitance of 87.67 F g-1. Meanwhile, the asymmetric supercapacitor (ASC) device exhibits a high energy density of 27.4 Wh kg-1 at a power density of 750 W kg-1.

Preparation of CoS2 supported flower-like NiFe layered double hydroxides nanospheres for high-performance supercapacitors.

Layered double hydroxides (LDHs) are a kind of classic pseudocapacitive materials with lamellar structure and large specific surface area, which have attracted swinging attention in the electrochemical energy storage area. The CoS2@Ni is synthesized through a hydrothermal process, followed by surface generation of the flower-like nickel-iron layered double hydroxide (NiFe-LDH) nanospheres through a hydrothermal process, which is directly used to design a binder-free electrode with a splendid capacitance capability. The as-synthesized NiFe-LDH@CoS2@Ni electrode presents an outstanding specific capacitance of 11.28 F cm-2 (3880 F g-1) at 2 mA cm-2 (1.17 A g-1) in a three electrodes system. Also, the all-solid-state asymmetric supercapacitor (ASC) is combined utilizing the NiFe-LDH@CoS2@Ni hybrid as the positive electrodes and active carbon covered Ni foam as negative electrodes, respectively. The as-fabricated ASC exhibits a high energy density of 15.84 Wh kg-1 at the power density of 375.16 W kg-1 and can be able to lighten a blue LED indicator for more than 30 min, revealing that the prepared NiFe-LDH@CoS2@Ni owns great potential in the aspect of practical applications. Therefore, the prepared NiFe-LDH@CoS2@Ni with outstanding electrochemical properties could be applied for high-performance supercapacitors.

Cobalt/Nickel Ions-Assisted Synthesis of Laminated CuO Nanospheres Based on Cu(OH)2 Nanorod Arrays for High-Performance Supercapacitors.

The development for environmentally friendly energy conversion and storage equipment has given rise to tremendous research efforts as a result of the growing requirements for environmental friendly resources and the rapid consumption of traditional fossil fuel. Herein, a novel hierarchical CoO/NiO-Cu@CuO heterostructure is successfully devised and synthesized. Cobalt/nickel ions are used to generate novel CoO/NiO-doped laminated CuO nanospheres through the facile in situ wet oxidation combined with cation exchange and calcination strategies. As a result, the electrochemical supercapacitance of the as-prepared CoO/NiO-Cu@CuO electrode can reach 875 C cm-2 (2035 mF cm-2), which exhibits much better electrochemical performance compared to other precursor electrodes at a same current density of 2 mA cm-2. Moreover, an excellent rate capacity of 1395 mF cm-2 (50 mA cm-2) can be achieved when measured at a relative high current density; 90.3% of the initial supercapacitance remains even after 5000 cycles. Furthermore, the as-prepared hierarchical hybrid of laminated CoO/NiO-CuO nanospheres in situ generated on three-dimensional (3D) porous Cu foam is applied to prepare a solid-state asymmetric supercapacitor equipment unit. The fabricated equipment unit shows an energy density of 69.3 W h kg-1 at a power density of 1080 W kg-1. Additionally, the commercially applied 2.5 V light-emitting-diode indicator with blue light can be energized for 4 min when two as-fabricated supercapacitor devices are in series connection. The unique hierarchical heterostructure of the novel laminated nanospheres combined with the 3D grid structure brings about the outstanding electrochemical capacitor performances. This strategy for the fabrication of hierarchical heterostructure electrodes could have an enormous potential for high-performance electrochemical equipment.

Improving the rate capability of ultrathin NiCo-LDH nanoflakes and FeOOH nanosheets on surface electrochemically modified graphite fibers for flexible asymmetric supercapacitors.

A fiber asymmetric supercapacitor system is designed with NiCo-LDH nanoflakes and FeOOH nanosheets anchored on electrochemically activated graphite fibers as positive electrode and negative electrode, respectively. Due to the formation of COMetal bonding, the oxygen-functionalized carbon on electrochemically activated graphite fibers can bind strongly with NiCo-LDH and FeOOH, which assists in establishing the fast electron transfer routes and fluent ion transport avenues. Both NiCo-LDH and FeOOH anchored on electrochemically activated graphite fibers display a high rate performance, 80% and 87.3% of the electric capacity can be reserved with the current density increasing from 2 to 20 A g-1 and 2 to 10 A g-1, respectively, while the NiCo-LDH and FeOOH deposited on untreated graphite fibers can only retain 45% and 40%. The fabricated novel solid-state fiber asymmetric supercapacitor device exhibits an expanded operation potential window of 1.8 V with a maximum energy density (130 W h kg-1) when the power density is 1.8 kW kg-1. Furthermore, a high energy density (81 W h kg-1) is still achieved at a superhigh power density (10.8 kW kg-1). Additionally, a good cycling stability of the solid-state fiber asymmetric supercapacitor can be obtained (90% capacity retention after 10,000 cycles).