Three-dimensional Foam Research Articles

Thermal behavior of Composite Material (nanoPCM/aluminum foam) used for thermal energy storage (TES) applications

Thermal energy storage systems (TESS) using phase change materials (PCM) have attracted interest in various fields of science and technology. However, the interest of these systems is limited by the relatively low thermal conductivity of PCMs and their leakage in the melted state. To overcome these drawbacks, the present paper suggests a new alternative for the enhancement of the PCMs by incorporating highly conductive materials, such as metal foam and/or nanoparticles. A Direct Numerical Simulation (DNS) was carried out to investigate the melting process of paraffin wax as PCM enhanced with alumina nanoparticles (i.e. nanoPCM) embedded in aluminum foam under constant temperature. A three-dimensional (3D) foam regular structure was designed. The effects of aluminum foam porosity and nanoparticles’ volume fraction on the thermal behavior of composite PCMs were investigated. The two-temperature model based on the assumption of local thermal non equilibrium was applied due to the great difference of thermal conductivity between nanoPCM and aluminum foam.

Hierarchical ZnO nanorod arrays grown on copper foam as an advanced three-dimensional skeleton for dendrite-free sodium metal anodes

Na metal is regarded as a potential anode material for next-generation Na metal batteries owing to its high theoretical capacity and low cost. However, the severe dendrite growth and infinitely volume changes of Na limit its practical applications as an anode material. In this study, a three-dimensional (3D) Cu foam skeleton with hierarchical ZnO nanorod arrays (CF@ZnO) was prepared as a stable host for dendrite-free Na metal anodes. Commercially available Cu foam was treated via a simple chemical precipitation method to grow hierarchical ZnO nanorod arrays, exhibiting a 3D porous structure with a cylindrical core-shell skeleton. The highly “sodiophilic” ZnO nanorod arrays provided abundant Na nucleation sites and exhibited low nucleation overpotential, which facilitated the homogeneous nucleation and uniform growth of Na on the electrode. Moreover, the 3D porous core-shell cylindrical structure of the nanorod arrays efficiently reduced the local effective current density, thus suppressing the growth of Na dendrites, as indicated by COMSOL Multiphysics simulations. As a result, the CF@ZnO electrode exhibited dendrite-free morphology during repeated Na plating/striping and excellent cycling stability with very small voltage hysteresis even at high current densities. When paired with a Na 3 V 2 (PO 4 ) 3 cathode, the CF@ZnO/Na electrode showed significant potential for application in full cells. This study provides a facile approach to design 3D sodiophilic hosts for high-energy-density Na metal batteries. • 3D Cu foam skeleton with hierarchical ZnO nanorod arrays have developed as a stable host for dendrite-free Na metal anode. • CF@ZnO electrode exhibited a dendrite-free morphology during repeated Na plating/striping and excellent cycling stability. • COMSOL Multiphysics simulations verified homogeneous nucleation and uniform growth of Na on the surface of CF@ZnO.

Self-supporting and 3D MoS2/MoO2/CNT/graphene foam as high-performance anode for lithium ion batteries

Three-dimensional (3D) MoS2/MoO2/carbon nanotube/graphene (MS/MO/CNT/G) foam has been prepared through hydrothermal reaction and freeze-drying process. The ratio of MoS2 to MoO2 can be controlled by changing pH of solvent during hydrothermal process. The electrochemical performance of MS/MO/CNT/G foam can be optimized through changing the ratio of MoS2 to MoO2. Graphene oxide (GO) and carbon nanotube (CNT) as carbon source are employed to build a three-dimensional foam. MoO2 enhances electronic conductivity and MoS2 provides high capacity. The flexible foam can be directly used as a self-supporting anode for lithium ion batteries. 3D MS/MO/CNT/G foam after the optimizing process exhibits high reversible capacity of 640 mAh g−1 at 100 mA g−1 after 200 cycles and 360 mAh g−1 at 1 A g−1 after 300 cycles when the pH was adjusted to 6.

A cast-in-place fabrication of high performance epoxy composites cured in an in-situ synthesized 3D foam of nanofibers

A cast-in-place process is usually adopted to prepare bicontinuous composites which display good mechanical properties and excellent comprehensive performance. But the construction of an intercommunicating porous skeleton seems to be cumbersome and low efficient. Here we report a three-dimensional nanofibers foam (3D NFF), which has been fabricated and applied to enhance epoxy resin composite. The 3D NFF skeletons with densities from 0.028 to 0.218 g/cm3 were fabricated by regulating the conditions for the nanofiber growth. The 3D NFFs were conveniently modified with a silane coupling agent to improve the interface interaction with the epoxy matrix. Compared to the pure epoxy, the compressive strength of the cast-in-place processed 3D NFFs/epoxy composite was improved by 436.8% at loading of 3.9 wt%, and the flexural strength was increased by 133.5% at loading of 5.3 wt%. While the compressive and flexural strength of the NFPs/epoxy composite prepared through traditional mixing method was increased by 173.6% at loading of 3.9 wt%, and 63.1% at loading of 5.3 wt%, respectively.

Three-dimensional heterostructures of Co@CuxS core–shell nanowire arrays as efficient bifunctional electrocatalysts for overall water splitting

Developing low-cost, efficient and stable bifunctional electrocatalysts for overall water splitting is very necessary to meet the demand for green H2 fuel in the near future. In this work, we have developed a novel hierarchical heterostructure of CuxS nanosheets/Co nanowire arrays supported on three-dimensional Ni foam (Co@CuxS NWs/3D-NF) as highly active bifunctional electrocatalysts for both the hydrogen (HER) and oxygen (OER) evolution reactions. Inheriting from the advantage of core-shell heterostructure, mesoporous characteristic and chemical coupling effect between Co core and CuxS shell layer, the as-synthesized Co@CuxS NWs/3D-NF exhibits high catalytic activity toward HER and OER with requiring small overpotential of 104.6 and 292.2 mV to reach current density of 10 mA cm−2, respectively. Furthermore, assembled Co@CuxS NWs/3D-NF-based electrolyzer shows remarkable performance with a low operating voltage of 1.55 V at 10 mA cm−2 and high long-term stability, which offers a favorable evidence for potential of our catalyst in practical application.

CuNi alloy/ carbon foam nanohybrids as high-performance electromagnetic wave absorbers

Three-dimensional (3D) carbon foams (CF) embedded with CuNi alloy nanoparticles have been constructed for electromagnetic wave absorption application. In the synthetic procedure, Ni2+ and Cu2+ were firstly adsorbed into the melamine foam (MF) to form Ni2+-Cu2+/MF composites, which were then subject to the pyrolysis treatment, resulting in the production of mesoporous CuNi alloy/CF. The texture characterizations indicate that CuNi alloy nanoparticles whose size distribution was 20–600 nm were embedded on the surface of the CF. Other than previous carbon structures, the CuNi/CF with CuNi alloy nanoparticles evenly distributed into the 3D carbon matrix inherits the characteristic of the 3D structured N-rich MF, which induces masses of dipole polarization, interfacial polarization and electromagnetic wave scattering. The CuNi11 exhibits excellent electromagnetic wave absorption performance with the reflection loss (RL) of −50.20 dB at a thin thickness of 1.6 mm. This work highlights the effect of metal compositions on the electromagnetic wave absorption performance and provides an environmentally friendly, low cost and easy-to-large-scale-preparation approach for the design of metal alloy/CF electromagnetic wave absorbers.

Two-Dimensional Molecular Sheets of Transition Metal Oxides toward Wearable Energy Storage.

Flexible and wearable electronics have recently sparked intense interest in both academia and industry because they can greatly revolutionize human lives by impacting every aspect of our daily routine. Therefore, developing compatible energy storage devices has become one of the most important research frontiers in this field. Particularly, the development of flexible electrodes is of great significance when considering their essential role in the performance of these devices. Although there is no doubt that transition metal oxide nanomaterials are suitable for providing electrochemical energy storage, individual oxides generally cannot be developed into freestanding electrodes because of their intrinsically low mechanical strength.Two-dimensional sheets with genuine unilamellar thickness are perfect units for the assembly of freestanding and mechanically flexible devices, as they have the advantages of low thickness and good flexibility. Therefore, the development of metal oxide materials into a two-dimensional sheet morphology analogous to graphene is expected to solve the above-mentioned problems. In this Account, we summarize the recent progress on two-dimensional molecular sheets of transition metal oxides for wearable energy storage applications. We start with our understanding of the principle of producing two-dimensional metal oxides from their bulk-layered counterparts. The unique layered structure of the precursors inspired the exploration of their interlayer chemistry, which helps us to understand the processes of swelling and delamination. Rational methods for tuning the chemical composition, size/thickness, and surface chemistry of the obtained nanosheets and how physicochemical properties of the nanosheets can be modulated are then briefly introduced. Subsequently, the orientational alignment of the anisotropic sheets and the origins of their liquid-crystalline characteristics are discussed, which are of vital importance for their subsequent macroscopic assembly. Finally, macroscopic electrodes with geometric diversity ranging from one-dimensional macroscopic fibers to two-dimensional films/papers and three-dimensional monolithic foams are summarized. The intrinsically low mechanical stiffness of metal oxide sheets can be effectively overcome by wisely designing the assembly mode and sheet interfaces to obtain decent mechanical properties integrated with superior electrochemical performance, thereby providing critical advantages for the fabrication of wearable energy storage devices.We expect that this Account will stimulate further efforts toward fundamental research on interface engineering in metal oxide sheet assembly and facilitate wide applications of their designed assemblies in future new-concept energy conversion devices and beyond. In the foreseeable future, we believe that there will be a big explosion in the application of transition metal oxide sheets in flexible electronics.

Direct MOCVD Growth of Iron Oxide on Three-Dimensional Nickel Foam as Electrode for the Oxygen Evolution Reaction.

Iron oxide thin films were grown directly on three‐dimensional nickel foam via metalorganic chemical vapor deposition (MOCVD) in the temperature range of 250–450 °C using Fe(CO)5 as precursor. Iron oxide (α‐Fe2O3) films were formed at low substrate temperatures (250–350 °C), whereas the additional growth of an underlying NiO film occurred at substrate temperatures above 350 °C. The electrochemical activities of the as‐formed binder‐free and noble metal‐free electrodes were tested for the oxygen evolution reaction (OER) in alkaline media. An overpotential reduced by 250 mV at a current density of 50 mA cm−2 and a lower Tafel slope of 55 mV dec−1 compared to bare nickel foam were found for the best‐performing electrocatalyst, while the long‐term stability of the as‐formed electrodes was proven by chronopotentiometry. The surface morphology of the iron oxide films was characterized by scanning electron microscopy, whereas the crystallographic phase as well as the elemental composition were determined by X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy, and time‐of‐flight secondary ion mass spectrometry in the pre‐ and the post‐catalytic state.

Nanosheets based mixed structure CuCo2O4 hydrothermally grown on Ni foam applied as binder-free supercapacitor electrodes

• Nanosheets mixed structure CuCo 2 O 4 on Ni foam was synthesized by a facile hydrothermal reaction. • Nanosheets mixed structure CuCo 2 O 4 show the superior electrochemical performances. • CuCo 2 O 4 nanosheets exhibit specific capacitance of 1595 F g −1 at 1 A g −1 and good cycling stability. CuCo 2 O 4 has been successfully hydrothermally grown on Ni foam. The morphology of the sample are observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The product has a unique morphology based on nanosheets which can self-assembly into two main structure. The electrode exhibits good electrochemical performance in supercapacitor application. The specific capacitance is 1595 F g −1 at 1 A g −1 , and specific capacitance keeps 85.1% after 4600 cycles. Such performance may be responsible for some factors. Three-dimensional Ni foam can be regarded as a conductive skeleton and firm substrate. It can further enhance the conductivity by not using binders. The unique mixed structure can provide more exchange between electrode and electrolyte. Both faster electron transmission and shorter ion diffusion path facilitate the redox reactions which can improve the electrochemical performance. The results indicate the nanosheet based mixed structure CuCo 2 O 4 grown on Ni foam have a promising future as supercapacitor electrodes. CuCo 2 O 4 nanosheets grown on Ni foam applied as binder-free electrode of supercapacitor shows an impressive enhancement of the performance including the areal capacitance and cycling stability.

Meso-Complexity Computer Simulation Investigation on Antiexplosion Performance of Double-Layer Foam Aluminum under Pore Grading

Foam aluminum is an energy-absorbing material with excellent performance. The interlayer composed of multiple layers of foam aluminum and steel plate has good antiexplosion ability. In order to explore the antiexplosion performance of double-layer foam aluminum under different porosity rankings and to reveal its microscopic deformation law and failure mechanism, three kinds of aluminum foams with a porosity of 80%, 85%, and 90% were selected to form six different structures. Based on the Voronoi algorithm, a three-dimensional foam aluminum generation algorithm with random pore size and random wall thickness was written by using the Python language and Fortran language. The three-dimensional mesoscopic model of double-layer closed-cell aluminum foam sandwich panel is established by using LS-DYNA and ABAQUS software. The explosion process was simulated, and the flow field movement of explosion shock wave of aluminum foam under different porosity rankings was analyzed. Two groups of aluminum foam were randomly selected for the explosion test and compared for the strain and compression. The test results are consistent with the simulation results, which verifies the correctness of the three-dimensional meso-model. The results show that when the porosity of the upper layer of aluminum foam is greater than that of the lower layer of aluminum foam, the sandwich structure of double-layer aluminum foam has a large compression and the bottom plate has a small displacement; it is not that the greater the compression amount of aluminum foam is, the better the antiexplosion and wave absorption ability is. When the aluminum foam reaches the ultimate load-bearing capacity, the aluminum foam transfers the load due to compaction, resulting in stress enhancement phenomena. Through the analysis of the compression amount, floor deformation, wave dissipation capacity, and energy ratio of aluminum foam, it is concluded that the antiexplosion wave absorption effect of the sandwich structure of aluminum foam with 80%/85% group is the best; the changes of porosity and cell wall are important factors affecting the energy absorption capacity of aluminum foam.

Study on blast resistance of a composite sandwich panel with isotropic foam core with negative Poisson's ratio

In this paper, a sandwich panel composed of two metal face sheets and a three-dimensional (3D) isotropic foam core with negative Poisson's ratio (NPR) was established via FEM. The 3D NPR isotropic foam core was achieved by using triaxial compression method on a cubic Voronoi model, which was created based on Voronoi tessellation technique to achieve different randomness for the core (β). The Poisson's ratio of the Voronoi core dropped rapidly at first, and then increased with an increasing triaxial pre-compression ratio η. A minimum Poisson's ratio, −0.12, was obtained when the randomness of the Voronoi core β = 0.29 and the triaxial pre-compression ratio η = 0.4. The blast resistance of the proposed composite sandwich panel (CSP) with cores that have different β and η under 300 g equivalent TNT explosion was analyzed. Results show that with an increase of η, the maximum stress on the foundation surface of CSPs gradually decreased, and then slightly increased. The maximum stress on the foundation surface of CSPs can reach a minimum value when β = 0.29 and η = 0.4. The proposed CSP with the minimum Poisson's ratio core exhibited the highest blast resistance performance, which was approximately 1.5 times higher than CSP with traditional re-entrant NPR structure core.

Hierarchical Cu3P-based nanoarrays on nickel foam as efficient electrocatalysts for overall water splitting

Exploring the efficient bifunctional catalysts and binder-free electrode materials for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is receiving continuous interest. Herein, we report the fabrication of hierarchical copper phosphide nanoarrays (Cu3P) on three-dimensional (3D) nickel foam (NF) through a template-directed synthetic strategy as electrocatalysts for overall water splitting. Specifically, the Cu3P/NF electrode demonstrates a remarkably low overpotential of ∼331 mV to approach the current density of 50 mA cm−2 in the OER, and an overpotential of ∼115 mV to achieve −10 mA cm−2 current density in the HER. Meanwhile the Cu3P/NF catalyst could hold a great stability for both reactions in alkaline condition, reflected in 37 h for OER and 24 h for HER of consistent galvanostatic electrolysis. As revealed by TEM, STEM and XPS characterizations, the high catalytic OER activity can be ascribed to the 3D open structure of Cu3P/NF and the abundant CuO active sites in hierarchical CuO/Cu3P/NF structure after in-situ activation. Furthermore, the overall water splitting is conducted in a two-electrode cell, which requires only a cell voltage of 1.63 V to approach 10 mA cm−2 with a good stability of 20 h. This protocol of Cu3P/NF electrode affords a general strategy to construct hierarchically structured metal phosphides for clean energy-related application.

Robust Bifunctional Compressed Carbon Foam for Highly Effective Oil/Water Emulsion Separation.

In this study, we report the pure compressed carbon foam (CCF) that offers a brand-new solution for separating emulsified oil/water mixtures. The CCF was fabricated by low-temperature carbonization of three-dimensional commercial melamine foam, which was then compressed without any further chemical modification. The CCF has amphiphilicity in air, underwater superoleophobicity, and underoil superhydrophobicity; therefore, it has been proved to be successfully utilized in highly emulsified oil-in-water and water-in-oil emulsions with excellent separation efficiencies, and it merely relies on gravity in the absence of external force. The CCF can also maintain its superwetting property under different harsh conditions, including strong acid, alkali, and salt solution conditions; this property offers great opportunities for widespread applications. Importantly, the CCF exhibits excellent permeability, separation efficiency, antifouling, and reusability performance. This novel CCF material has great potential application in handling oily wastewater owing to its low-cost raw materials, easily scaled-up preparation process, excellent antifouling property, and high separation capacity of materials.

Facile One-Step Preparation of 3D Nanoporous Cu/Cu6Sn5 Microparticles as Anode Material for Lithium-Ion Batteries with Superior Lithium Storage Properties

In this article, three-dimensional nanoporous Cu/Cu6Sn5 microparticles (3D-NP Cu/Cu6Sn5 MPs) were prepared by one-step chemical dealloying of Cu20Sn80 (at%) alloy slices in a mixed aqueous solution of HF and HNO3 and then filled into a three-dimensional porous copper foam (3D-PCF) skeleton as anode (3D-PCF@Cu/Cu6Sn5) for lithium-ion batteries (LIBs). The results show that the ellipsoidal 3D-NP Cu/Cu6Sn5 MPs with feature sizes of 3 to 8 μm are composed of numerous uniform nanoparticles (100 to 200 nm) and plenty of voids. Compared with similar Sn-based electrodes in this work and other published reports, the as-prepared electrode delivers more outstanding electrochemical performance with a superior reversible capacity of 1.90 mAh cm−2, 84.44% capacity retention and > 99.5% coulombic efficiency upon 200 cycles. The cycling stability and integrity of the overall structure of the composite electrode have been greatly enhanced under the synergistic effect of the buffer effect of copper as the inactive component, the unique hierarchical porous electrode architecture and the effective limitation in three dimensions of the 3D-PCF skeleton. We are confident that this work can provide new-generation LIBs with a promising anode candidate and a facile method of dealloying, and a subsequent filling step can achieve the practical production and application of high-performance LIBs.

MoS2/graphene/carbonized melamine foam composite catalysts for the hydrogen evolution reaction

A melamine-based carbon foam was obtained from a melamine foam (2×2×2 cm3), which was then coated with graphene by immersing it in 400 mL of a suspension of reduced graphene oxide in water with concentrations of 25 to 100 mg/L. MoS2/graphene/carbonized melamine foam composites for use as catalysts for the hydrogen evolution reaction were synthesized by the hydrothermal growth of MoS2 nanosheets on the graphene-coated carbon foams in a mixed solution of molybdic acid disodium salt and thiourea. Results indicate that MoS2 nanosheets with a thickness of 15–20 nm were uniformly distributed on the three-dimensional carbon foam substrates coated with different amounts of graphene. The amount of graphene coating has a great influence on the hydrogen evolution performance. The composite prepared with a graphene concentration of 25 mg/L has the best electrochemical performance, its initial overpotential at a 10 mA cm–2 current density is 163 mV, and the corresponding Tafel slope is 76 mV dec–1. It has also the lowest impedance, which shows that coating the carbon foam with an appropriate amount of reduced graphene oxide accelerates electron migration and improves the hydrogen evolution performance.

NiFe-Layered Double Hydroxide Synchronously Activated by Heterojunctions and Vacancies for the Oxygen Evolution Reaction.

The development of earth-abundant transition-metal-based electrocatalysts with bifunctional properties (oxygen evolution reaction (OER) and hydrogen evolution reaction (HER)) is crucial to commercial hydrogen production. In this work, layered double hydroxide (LDH)-zinc oxide (ZnO) heterostructures and oxygen vacancies are constructed synchronously by plasma magnetron sputtering of NiFe-LDH. Using the optimal conditions, ZnO nanoparticles are uniformly distributed on the NiFe-LDH nanoflowers, which are prepared uniformly on the three-dimensional porous Ni foam. In the LDH-ZnO heterostructures and oxygen vacancies, electrons are depleted at the Ni cations on the NiFe-LDH surface and the active sites change from Fe cations to Ni cations during OER. Our theoretical assessment confirms the change of active sites after the deposition of ZnO and reveals the charge-transfer mechanism. Owing to the significant improvement in the OER dynamics, overall water splitting can be achieved at only 1.603 V in 1 M KOH when the Ni/LDH-ZnO and Ni/LDH are used as the anode and cathode, respectively. The work reveals a novel design of self-supported catalytic electrodes for efficient water splitting and also provides insights into the surface modification of catalytic materials.

Highly efficient electrochemical gas reduction on a three-dimensional foam electrode: mechanism and application for the determination of hazardous mercury in complex matrix.

For the first time a nickel foam electrode (NFE) is appliedin the field of electrochemical vapor generation (EVG) to carry out the electrochemical vapor phase conversion of mercury. Systematical electrochemical and morphological research has demonstrated that the specific surface area of the NFE was several times larger than that of the metal/non-metal electrode with the same geometric size. At the same time, the 3D porous channel composed of multi-layer nickel wire ensures the full contact between reactant and interface. The evident enhancement of spectral signals on aNi electrode (283%), compared with Pt (27%) and graphite (109%), confirmed that the NFE effectively enhances the yield of mercury reduction. The NFE exhibits low limit of detection (0.017μgL-1) and awide linear range (0.2-20μgL-1) with recoveries of actual samples in the range 87.8-117% towards Hg2+. Although the NFE has no advantage in electronic transmission and catalytic performance, its excellent stability, especially anti-interference and other characteristics, is sufficient for the analysis of hazardous mercury in complex matrix including certified reference materials and real samples.

Regulation of the electronic structure of Co4N with novel Nb to form hierarchical porous nanosheets for electrocatalytic overall water splitting

Heretofore, the metal elements constituting the electrolyzed water catalysts are almost all Fe, Co, and Ni, and the accelerator elements are V, W, Ce, etc., but there is a lack of exploration for other elements. Niobium (Nb) is a promising promoter due to its complex chemical properties and the ability to react with many elements to form abundant compounds. Taking Co4N as the research case, this work incorporates Nb atoms to tune the d orbital of metallic Co4N nanowires. Experimental results and density functional theory calculations show that due to the adjustment of Nb atoms, the d-band center of Co4N moves down, which helps facilitate the desorption of H2. At the same time, abundant Co3+ active sites are generated on the surface of Nb–Co4N, which is crucial for the formation of oxygen evolution reaction (OER) intermediates (∗OOH). Nb-regulated Co4N nanosheets on the three-dimensional Ni foam (Nb–Co4N/NF) drives the current density of 20 mA cm−2 at a low overpotential of 90 mV for hydrogen evolution reaction and 273 mV for OER, respectively. This work inspires a novel idea for the rational design and synthesis of highly efficient electrocatalysts composed of novel less used elements for overall water splitting.

Multi-dimensionally hierarchical self-supported Cu@Cu2+1O@Co3O4 heterostructure enabling superior lithium-ion storage and electrocatalytic oxygen evolution

Here, we propose a multi-dimensionally hierarchical self-supported Cu@Cu2+1O@Co3O4 heterostructure as superior bifunctional material for lithium-ion storage and electrocatalytic oxygen evolution via rapid in-situ oxidation-electrodeposition-annealing treatment. The 3/1/2-dimensional hybridization heterostructure rationally organized by three-dimensional Cu foam, one-dimensional Cu2+1O nanowires and two-dimensional Co3O4 nanosheets achieves remarkable synergistic interactions. In brief, the free-standing Cu foam framework enables remarkable structure robustness, electronic conductivity and electrolyte infiltration. Meanwhile, the in-situ grown Cu2+1O nanowires with excess metal defects indeed provide certain activity, effectively adjust the size and distribution of anchored Co3O4 nanosheets and dramatically shorten the diffusion pathway of ions and electrons. Moreover, the constructed interfaces between Cu2+1O and Co3O4 further yield sufficient electrochemically active surface area. In consequence, Cu@Cu2+1O@Co3O4 heterostructure delivers superior lithium-ion storage capacity and electrocatalytic oxygen evolution activity. Specifically, a prominent and stable discharge capacity of 1090 mAh g−1 can be delivered after 200 cycles at 500 mA g−1. Even when the current density is elevated to 5000 mA g−1, remarkable discharge capacity of 601 mAh g−1 still can be yielded. As for the electrocatalytic oxygen evolution activity, Cu@Cu2+1O@Co3O4 heterostructure demonstrates a particularly low overpotential of 223 mV at 10 mA cm−2 and Tafel slope of 46.3 mV dec−1. This strategy may enlighten the researchers on the further development of electrochemically active materials for advanced electrode and catalyst.

3D hierarchical flower-like NiMoO4@Ni3S2 composites on Ni foam for high-performance battery-type supercapacitors

A hydrothermal method was used to prepare a hierarchical flower-like NiMoO4@Ni3S2 composite on a three-dimensional Ni foam substrate, and the effects of different amounts of ethylene glycol in the precursor solution on the morphology and performance of Ni@NiMoO4@Ni3S2 were investigated. The as-synthesized No-10/Ni3S2 electrode exhibits a specific capacity up to 870 C g−1 at 0.6 A g−1 and excellent cycle stability (capacity retention of 81.2% after 8000 cycles). More importantly, in a hybrid supercapacitor with a No-10/Ni3S2 as a positive electrode and activated carbon (AC) as a negative electrode (No-10/Ni3S2//AC), the energy density of 128.31 W h kg−1 at a power density of 7106.4 W kg−1. As displayed, the performances make No-10/Ni3S2 a promising candidate as high-performance electrode material for supercapacitors.