Core-shell Arrays Research Articles

Two-step fabrication of hierarchical Ni(OH)2@NiCo2O4 core-shell nanoneedle array for highly efficient decoupled water splitting

The temporal and spatial segregation of the hydrogen and oxygen evolution reactions (HER and OER) are essential for advancing membrane-free electrolysis technology in H2 production through water splitting. This investigation employed a two-step fabrication approach to craft a three-dimensional self-supporting buffered electrode. This method involved utilizing a Ni(OH)2@NiCo2O4 core-shell nanoneedle array as the active material and nickel foam (NF) as the substrate. Remarkably, the H2 production at the cathode displayed remarkable efficiency, maintaining an uninterrupted operation duration of 1500 s at a current of 100 mA. Simultaneously, the Ni(OH)2@NiCo2O4 mediator on the anodic electrode underwent oxidation during this process, leading to the generation of its respective oxidized state, accompanied by a noteworthy operating voltage of 1.50 V. Afterwards, the second step of the OER involved the recovery of the buffered electrode and the generation of O2 at an operational voltage of 0.46 V, with the O2-production duration being equivalent to that of the first step in the HER process. Interestingly, the revival process of the buffered electrode in the second step can also be coupled with zinc sheets, thereby constructing a battery. During the discharge process of the battery, the regeneration of the buffered electrode was achieved, and this discharge process could also provide a power supply for the first step of H2-evolution. Therefore, this decoupled water electrolysis system presents a promising avenue for facilitating the effective transformation of renewable sources into hydrogen.

Designing core-shell heterostructure arrays based on snowflake NiCoFe-LTH shelled over W2N-WC nanowires as an advanced bi-functional electrocatalyst for boosting alkaline water/seawater electrolysis

The pursuit of efficient and sustainable hydrogen production through water splitting has led to intensive research in the field of electrocatalysis. However, the impediment posed by sluggish reaction kinetics has served as a significant barrier. This challenge has inspired the development of electrocatalysts characterized by high activity, abundance in earth's resources, and long-term stability. In addressing this obstacle, it is imperative to meticulously fine-tune the structure, morphology, and electronic state of electrocatalysts. By systematically manipulating these key parameters, the full potential of electrocatalysts can unleash, enhancing their catalytic activity and overall performance. Hence in this study, a novel heterostructure is designed, showcasing core–shell architectures achieved by covering W2N-WC nanowire arrays with tri-metallic Nickel-Cobalt-Iron layered triple hydroxide nanosheets on carbon felt support (NiCoFe-LTH/W2N-WC/CF). By integrating the different virtue such as binder free electrode design, synergistic effect between different components, core–shell structural advantages, high exposed active sites, high electrical conductivity and heterostructure design, NiCoFe-LTH/W2N-WC/CF demonstrates striking catalytic performances under alkaline conditions. The substantiation of all the mentioned advantages has been validated through electrochemical data in this study. According to these results NiCoFe-LTH/W2N-WC/CF achieves a current density of 10 mA cm−2 needs overpotential values of 101 mV for HER and 206 mV for OER, respectively. Moreover, as a bi-functional electrocatalyst for overall water splitting, a two-electrode device needs a voltage of 1.543 V and 1.569 V to reach a current density of 10 mA cm−2 for alkaline water and alkaline seawater electrolysis, respectively. Briefly, this research with attempting to combination of different factors try to present a promising stride towards advancing bi-functional catalytic activity with tailored architectures for practical green hydrogen production via electrochemical water splitting process.

Design and construction of hollow metal sulfide/selenide core-shell heterostructure arrays for hybrid supercapacitor.

Transition metal sulfides and selenides are common electrode materials in supercapacitors. However, the slow redox kinetics and structural collapse during charge-discharge cycles of single-component materials have impeded their electrochemical performance. In this study, hollow Co9S8 nanotubes were synthesized through a rational morphology design approach. Subsequently, NiSe2 or Co0.85Se was electrodeposited onto the Co9S8 nanotubes, yielding two core-shell heterostructure arrays, namely, NiSe2@Co9S8 and Co0.85Se@Co9S8. By fully leveraging the advantages and synergistic effects of these dual-phase heterostructures, the NiSe2@Co9S8 and Co0.85Se@Co9S8 configurations demonstrated outstanding areal capacitances of 12.54 F cm-2 and 9.61 F cm-2, respectively, at 2 mA cm-2. When integrated with activated carbon in hybrid supercapacitors, the NiSe2@Co9S8//AC and Co0.85Se@Co9S8//AC devices exhibited excellent energy storage performance, with energy densities of 0.959 mW h at 1.681 mW and 0.745 mW h at 1.569 mW, respectively. Additionally, these hybrid supercapacitors demonstrated remarkable cycling stability, with capacitance retention of 87.5% and 89.5% after 5000 cycles for NiSe2@Co9S8//AC and Co0.85Se@Co9S8//AC, respectively. This study provides a novel approach to the synthesis of multiphase core-shell heterostructures based on metal sulfides and selenides, opening new avenues for future research.

Improved ZnWO4@NiCo2O4 core-shell nanosheet arrays with regulatory interfaces and electronic redistribution.

ZnWO4@NiCo2O4 core-shell nanosheet array composites are synthesized on nickel foam via a two-step hydrothermal method. The optimal conditions, including a Ni(NO3)2·6H2O to Co(NO3)2·6H2O molar ratio of 2 : 1, 12 hours reaction time, and 120 °C temperature, yield a specific capacitance of 875 C g-1 at 1 A g-1. The electrode also maintains 81.1% capacitance after 10 000 cycles. The material's performance is attributed to its core-shell structure, which enhances ion diffusion and electron transport. This study presents a viable approach for high-performance supercapacitor electrodes.

Core-shell metallic nanotube arrays for highly sensitive surface-enhanced Raman scattering (SERS) detection

Here, we demonstrate the application of highly ordered, periodic Ag/Au core-shell triangle nanotube arrays as an ultrasensitive and low-cost surface-enhanced Raman scattering (SERS) substrate for the first time. The arrays of core-shell nanotube, with an outer diameter of 1.5 μm, were fabricated using top-down wafer-scale lithography followed by sequential sputter deposition of Ag and Au. The SERS activity of various combinations of core-shell structures was evaluated. It was found that Ag-core nanotubes overlaid with the Au-shell resulted in the highest Raman intensity, where the enhancement factor for R6G as a probe molecule is determined to be 1.38 × 107. Meanwhile, the limit of detections for R6G and ketoprofen analytes was evaluated to be 10−10 and 10−6 M, respectively. Linear correlations between the SERS signal intensities and logarithmical scale of both analytes in different concentrations were also established, ranging 10−4–10−10 and 10−2–10−6 M for R6G and ketoprofen, respectively. The Raman R6G peak intensity mapping suggests our metal nanotube arrays act as effective plasmonic hotspots and, thus, are useful for SERS sensing applications.

Dynamically Metasurface-Modulated Electrochemiluminescence Polarization Coupling Angle Strategy for miR-142-3p Detection.

The combination of the electrochemiluminescence (ECL) technique with nanophotonics research can spark new analytical and sensing applications. Herein, we developed a novel modulation strategy of the ECL polarization angle based on the dynamically tunable few-layer metasurface. The bilayer metasurface consisted of a fixed Au-Ag core-shell nanocube array (Au@Ag NCA) layer with strong plasmonic hot spots and different amounts of the Au nanoparticles@MoS2 heterostructure nanosheet (0D-2D HNS) layer with strong metal-support interaction. Due to the interference and near-field coupling between layers, the bilayer metasurface can strongly redistribute the local electromagnetic field and energy in the ECL system, which not only significantly amplified the ECL signal but also modulated the polarization coupling angle. Therefore, the novel ECL polarization angle-resolved sensing strategy has been developed, which was beneficial to improve the sensitivity and resolution of ECL sensing. A dynamically tunable metasurface-based ECL biosensor was successfully used to detect the asthma-related miRNA-142-3p (miR-142-3p). Moreover, the simulation calculations of the electromagnetic field revealed the unique optical activity of the metasurface. This study brought the insightful understanding of the metasurface-modulated optical signal and provided a new idea to construct novel sensing platforms.

High energy density pouch-type supercapacitor achieved by MOFs derived 3D hollow N-doped carbon with Fe2O3 and hierarchical CuCo2S4@NiFe-LDH core-shell nanostructures

The multicomponent rational control and distinctive architectural design of electrode materials remain critical factors for enhancing the energy density of supercapacitors. Herein, metal-organic framework (MOF)-derived three-dimensional (3D) hollow nitrogen-doped carbon (NHCs) with Fe2O3 core-shell composite negative electrode materials (NHCs@Fe2O3) were developed. In this framework, 1) the high specific surface area caused by the distinctive core-shell structure facilitated the electrolyte infiltration in the hollow skeleton, which shortened the ion transport path and enabled fast electron transfer; and 2) the synergistic effect of the nitrogen-containing groups of the hollow carbon and the reversible Faraday reaction of metal oxides increased the ratio of the pseudocapacitance. These phenomena were the primary reasons for the enhanced capacity of the core-shell electrode. Additionally, hierarchical CuCo2S4@layered double hydroxide (NiFe-LDH) nanobelt core-shell heterostructure arrays integrated on the nickel foam were used for the positive electrode materials. The asymmetric pouch-type supercapacitor assembled with NHCs@Fe2O3 (negative electrode) and CuCo2S4@NiFe-LDH (positive electrode) exhibited a high energy density of 68.6 W h kg–1 at a power density of 828.9 W kg–1. This work offers an effective strategy for fabricating multicomponent core-shell materials and optimizing the interactions between the components to enhance the electrochemical performance in energy storage applications.

Ni0.85Se@CoFe LDH heterostructure nanosheet arrays on Ni foam as efficient electrocatalysts for enhanced oxygen evolution

Exploring high-efficient, earth-abundant and stable electrocatalyst for oxygen evolution reaction (OER) is of vital importance for large-scale implementation of energy converting and storing. Thus, we fabricated a free-standing hierarchical heterostructure electrode of Ni0.85Se@CoFe LDH/NF via a rational combination of hydrothermal, selenization and electrodeposition process, among which the ultrathin CoFe LDH nanosheets intimately assembled onto the vertical aligned Ni0.85Se nanosheets supported on Ni foam. The constructed core-shell nanosheet arrays hold the plentiful hetero-interfaces and intimate interactions through metal-oxygen bonds between two individuals, which guarantee the fast OER kinetic processes. Additionally, CoFe LDH with crystalline/amorphous hybrid structure favors providing more reaction sites. Remarkably, the optimal Ni0.85Se@CoFe LDH/NF binary composites possess outstanding OER activity with a low overpotential of ∼223 and 280 mV at 10 mA cm−2 and 100 mA cm−2 in alkaline solution as well as good durability. This research offers an alternative approach for improving electrocatalytic water splitting through constructing 3D hierarchical heterostructures.

Promoting the discoloration of PdO in low concentration H2 by using PdAu bimetallic catalyst for eye-readable hydrogen leakage detection

Developing reliable and low-cost optical hydrogen sensors for hydrogen leakage detection at room temperature is extremely important. It requires that hydrogen sensors have a remarkable and rapid color change in low concentration H2/air mixtures, which it is still quite challenging at present. Herein, we demonstrate an eye-readable hydrogen sensor based on Pd-decorated Au@PdO core-shell nanoparticle arrays (Pd-Au@PdO NAs). Pd-Au@PdO NAs show an obvious color change from brownish-yellow to yellow-gray in 1 v/v% H2/air and gray in 4 v/v% H2/air, with ΔE values of 8.1 and 22.5, respectively. Detailed investigation showed that, at the cracks of PdO shell where Au core is exposed, PdAu bimetallic catalyst is generated during the sample-synthesis process. Compared with Pd catalyst, PdAu bimetallic catalyst significantly prompts the reduction of PdO in low concentration H2, represented as a faster discoloration process and more obvious color change. Additionally, the core-shell structure ensures a long-term stability through protecting the PdAu catalyst. We further show that the irreversible sensing performance of Pd-Au@PdO NAs can be reactivated repeatedly, which favors extending the lifetime of the optical sensor and reducing the cost.

Scarless wound healing programmed by core-shell microneedles

Effective reprogramming of chronic wound healing remains challenging due to the limited drug delivery efficacy hindered by physiological barriers, as well as the inappropriate dosing timing in distinct healing stages. Herein, a core-shell structured microneedle array patch with programmed functions (PF-MNs) is designed to dynamically modulate the wound immune microenvironment according to the varied healing phases. Specifically, PF-MNs combat multidrug-resistant bacterial biofilm at the early stage via generating reactive oxygen species (ROS) under laser irradiation. Subsequently, the ROS-sensitive MN shell gradually degrades to expose the MN core component, which neutralizes various inflammatory factors and promotes the phase transition from inflammation to proliferation. In addition, the released verteporfin inhibits scar formation by blocking Engrailed-1 (En1) activation in fibroblasts. Our experiments demonstrate that PF-MNs promote scarless wound repair in mouse models of both acute and chronic wounds, and inhibit the formation of hypertrophic scar in rabbit ear models.

Controllable fabricate hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays for high-performance hybrid supercapacitor

Rational design and construction of multiphase composite with specifical structure is an effective strategy to fabricate high-performance supercapacitor electrode materials. Herein, the hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays are constructed by preparing Co9S8/Ni3S2 core with ion-exchange reaction and fabricating CoMoO3 shell through in situ transformation behavior. Thanks to the special heterostructures core-shell structure, the synergistic effect between multiple components, and the driving action of S-vacancies, hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays exhibit battery-type features and deliver a great area specific capacity of 8.14 C cm−2 at current density of 5 mA cm−2. In addition, when assembled into a hybrid supercapacitor with capacitive-type electrode, the device achieves high energy density of 0.33 mWh cm−2 at the power density of 5.66 mW cm−2 and displays long-term durability with capacity retention of 93.7% and high Coulombic efficiency of 95.01% after 6000 cycles.

Rational design of binder free NiFe2O4@CoFe2O4 core–shell nanoflake arrays synthesized by chemical bath deposition for supercapacitor application

In recent years, exploiting stable and high-performance electrode materials has attracted researchers interest as the demand for clean, efficient, and sustainable energy storage devices grows. In this study, facile NiFe2O4@CoFe2O4 core-shell nanoflake arrays grown on flexible stainless steel mesh (FSSM) were synthesized by a simple, low-cost two-step chemical bath deposition (CBD) method. The synergistic influence between NiFe2O4 nanoflake arrays and CoFe2O4 nanoflakes in the mesh form electrode that show a quick electron/ion transfer and a higher electrical conductivity. The NiFe2O4@CoFe2O4 core-shell nanoflake array electrode has shown a capacitance of 1459.4 F g−1 at a current density of 4 mA cm−2, which is significantly higher than the capacitances of the pristine NiFe2O4 and CoFe2O4 electrode. The NiFe2O4@CoFe2O4 core-shell nanoflake array electrode shows superb cycling stability with 85 % retention over 5000 cycles at a high current density of 20 mA cm−2. Furthermore, the NiFe2O4@CoFe2O4 core-shell nanoflake array symmetric device demonstrated a high energy density of 21.15 W h kg−1 at a power density of 0.466 k W kg−1. The improved electrochemical performance is attributed to its unique hierarchical structure, which allows for efficient ion and electron transport, a high number of active sites, and a synergistic impact. This novel integrated nanoarchitecture could hold significant promise as improved electrodes for high-performance supercapacitors due to its remarkable electrochemical performance and cost-effective production procedure.

Superstructured NiMoO4@CoMoO4 core-shell nanofibers for supercapacitors with ultrahigh areal capacitance

High areal capacitance for a practical supercapacitor electrode requires both large mass loading and high utilization efficiency of electroactive materials, which presents a great challenge. Herein, we demonstrated the unprecedented synthesis of superstructured NiMoO4@CoMoO4 core-shell nanofiber arrays(NFAs) on a Mo-transition-layer-modified nickel foam (NF) current collector as a new material, achieving the synergistic combination of highly conductive CoMoO4 and electrochemical active NiMoO4. Moreover, this superstructured material exhibited a large gravimetric capacitance of 1,282.2 F/g in 2 M KOH with a mass loading of 7.8 mg/cm2, leading to an ultrahigh areal capacitance of 10.0 F/cm2 that is larger than any reported values of CoMoO4 and NiMoO4 electrodes. This work provides a strategic insight for rational design of electrodes with high areal capacitances for supercapacitors.

Micro-Nanoarchitectonics of Ga2O3/GaN Core-Shell Rod Arrays for High-Performance Broadband Ultraviolet Photodetection

This study presents broadband ultraviolet photodetectors (BUV PDs) based on Ga2O3/GaN core-shell micro-nanorod arrays with excellent performance. Micro-Nanoarchitectonics of Ga2O3/GaN core-shell rod arrays were fabricated with high-temperature oxidization of GaN micro-nanorod arrays. The PD based on the microrod arrays exhibited an ultrahigh responsivity of 2300 A/W for 280 nm at 7 V, the peak responsivity was approximately 400 times larger than those of the PD based on the planar Ga2O3/GaN film. The responsivity was over 1500 A/W for the 270–360 nm band at 7 V. The external quantum efficiency was up to 1.02 × 106% for 280 nm. Moreover, the responsivity was further increased to 2.65 × 104 A/W for 365 nm and over 1.5 × 104 A/W for 270–360 nm using the nanorod arrays. The physical mechanism may have been attributed to the large surface area of the micro-nanorods coupled with the Ga2O3/GaN heterostructure, which excited more photogenerated holes to be blocked at the Ga2O3 surface and Ga2O3/GaN interface, resulting in a larger internal gain. The overall high performance coupled with large-scale production makes it a promising candidate for practical BUV PD.

Assembling zinc cobalt hydroxide/ternary sulfides heterostructure and iron oxide nanorods on three-dimensional hollow porous carbon nanofiber as high energy density hybrid supercapacitor

The critical challenge of supercapacitors lies in sluggish kinetics of electrodes and undesirable specific capacitance during charge discharge process including large volume change and inferior cyclic stability. In this work an elaborately designed three dimensional hierarchical heterostructure comprising ternary metal sulfides completely covered by nickel cobalt layered double hydroxide (NiCo-LDH@ZNCS) core shell arrays on electrospun three-dimensional hollow porous carbon nanofiber and used as free-standing electrode material for supercapacitors. The original built-in interfacial potential between NiCo-LDH and ZNCS on conducting three dimensional hollow PCF can acquire multidimensional channels for ion/electron transfer and validate to be a highly capacitive cathode material with a high specific capacity of 407.11 mA h g−1 at the current density of 1 mA cm−2 maintaining outstanding rate performance. The iron oxide nanorods (Fe2O3-PCF) anode (216.15 mA h g−1 at the current density of 1 mA cm−2) match well to the cathode. Benefiting from the powerful synergistic effect, the assembled quasi solid state asymmetric supercapacitor can deliver ultrahigh energy density of 111.72 W h kg−1 at a power density of 243 W kg−1 and extra ordinary life cycle stability (95.2 % capacity retention after 20,000 charge discharge cycles). Such superior electrochemical performances are attributed to the multidimensional nanostructures, porous carbon networks, improved conductivity, and synergistic interaction between the active components of NiCo-LDH/ZNCS arrays. This approach provides a new perspective for rational design of high energy density hybrid supercapacitors, holding unbounded possibilities in this energy dependent world.

Photoassisted Li-ion de-intercalation and Niδ+ valence conversion win-win boost energy storage performance in Ni/CdS@Ni3S2-based Li-ion battery

The development of bifunctional electrode with photoactivity and lithium storage properties is critical for manufacturing high-efficiency solar energy conversion/storage integrated devices. Herein, for the first time, Ni foam supported Ni3S2 nanosheets covered CdS photocatalyst, a core-shell heterojunction nanorods array (Ni/CdS@Ni3S2), is employed as photoelectrode for photo-assisted lithium-ion batteries (PA-LIBs). The assembled PA-LIBs can be off-grid charged by net solar light and on-grid photoassisted charged/discharged, respectively. Without external bias voltage, the overall solar-to-electrical energy conversion efficiency reaches 0.11 %. In addition, during the photo-assisted charging/discharging processes, the solar to electricity energy conversion efficiency is increased to 3.5 % and 2.1 %, respectively, and the total special capacity of such photocell is significantly improved by 13.7 % and 15.9 % compared with its conventional electric energy charging/discharging battery. Impressively, the PA-LIB maintains good photo-responsive activity even after about 250 charge/discharge cycles. Mechanism investigation reveals that photo-assisted Li-ion de-intercalation and Niδ+ valence conversion together boosts the lithium-ion storage reaction more completely, thus improving the energy storage performance of Ni/CdS@Ni3S2-based Li-ion battery.

Sunlight-active hierarchical Ag@insulator@ZnO core-shell array based on natural diatoms for environmental remediation

A nature inspired plasmonic core-shell architecture was proposed by incorporating a natural siliceous insulator shell (Navicula salinicola frustules) in Ag/diatomite/ZnO hierarchical nanostructures to overcome the recombination of energetic charge carriers (e−/h+), corrosion of bare metal, and to facilitate the composite separation after reaction. The photocatalytic performance of the as-prepared composites, monitored by decomposition of methylene blue (MB), was investigated under both UV and simulated sunlight irradiation. Ag/diatomite/ZnO exhibited efficient photocatalytic performance (near 100% degradation and 95% mineralization) under simulated sunlight irradiation with apparent rate constant of 0.0246 min−1, which was found to follow pseudo-first order kinetics. The enhanced photocatalysis action of metal/insulator/semiconductor as compared to metal/semiconductor and the semiconductor alone could be ascribed to the synergistic effects of the photonic structure of regular frustules, improved sunlight harvesting efficiency, suppressed back electron transfer, and prohibited oxidization of Ag. While the as-synthesized composite was easy to separate from the reaction, however, it was in the throes of losing the photocatalytic activity after three rounds of reuse. A possible mechanism of photocatalytic degradation of MB induced by Ag/diatomite/ZnO under sunlight irradiation was proposed based on dye degradation measurements and reactive species trapping experiments. While the reusability of as-prepared composite will doubtless be much scrutinized, our study may provide a new insight into the design and fabrication of plasmonic-based nanomaterials for use in industry applications under solar light illumination.

Fabrication of hierarchical Ni nanowires@ NiCo-layered double hydroxide nanosheets core-shell hybrid arrays for high-performance hybrid supercapacitors.

Layered double hydroxides (LDHs) are electrode materials with high specific capacity due to their structure which has a tunable interlayer spacing, however, the disadvantages of their low conductivity and electrochemically limited sites prevent their application in supercapacitors. In this study, we synthesized a high electrochemical performance electrode material with a core-shell structure based on hierarchical nickel nanowires (core) and NiCo LDHs nanosheets (shell). First, hierarchical nickel nanowires, h-Ni NWs, were prepared by the reduction of Ni2+ ions by hydrazine N2H4. Then with the hydrothermal method, the hierarchical nickel nanowires were coated with NiCo LDHs to improve the electrical conductivity of the latter. The electrochemical results showed that the NiCo LDHs@h-Ni NWs electrode had a specific capacity of 1486 C/g at a current density of 1 A/g in 6 M KOH electrolyte with excellent capacity retention (89.7%) after 10,000 charge-discharge cycles at 20 A/g. Due to the synergistic interaction between nickel nanowires and NiCo LDHs which provides excellent conductivity, durability, efficient mesoporous network, and suitable channels for fast ion/electron transfer. In addition, a hybrid supercapacitor (HSC) was fabricated by combining the NiCo LDHs@h-Ni NWs electrode (battery type) with activated carbon (EDLC). The fabricated device provided a high energy density of 72.22 Wh/kg at 800 W/kg, and a maximum power density of 16 kW/kg, the HSC provided an energy density of 50.44 Wh/kg and outstanding cycling stability (88.1% retention after 10,000 cycles).

Core-shell 2D/2D FeCo2O4@Ni(OH)2 nano-on-microsheet array architecture for excellent asymmetric supercapacitor performance

Core-shell designed electrode architectures with favorable material components are a promising approach to enhance electrochemical performance. Herein, binder-free 2D/2D FeCo2O4@Ni(OH)2 core–shell architectures were successfully grown on a Ni-foam (NF) substrate, where the FeCo2O4 microsheets were hydrothermally processed following the electro-grafting of Ni(OH)2 nanosheets as a “shell” around a FeCo2O4 “core.” These core–shell array architectures were utilized as a discrete electrode system; they exhibited a high specific capacitance of 1944 F g−1 at a current density of 5 A g−1, which is better than the performance of individual FeCo2O4 and Ni(OH)2. This improved performance was attributed to the synergistic effects of the robust core–shell array architectures developed over the NF substrate as well as the enhanced electrical conductivity through electroactive sites at the interface while maintaining the structural integrity of the Ni(OH)2 shell. In addition, the two-electrode device was assembled constituting a FeCo2O4@Ni(OH)2 ΙΙ activated carbon asymmetric supercapacitor, resulting in a maximum energy density of 136 W h kg−1 and power density of 8500 W kg−1, with 78% capacitance retention and 93% coulombic efficiency over 5000 cycles at a current density of 8 A g−1. These results validate the effectiveness of this approach for improving the performance of energy storage devices.

Synthesis of the sandwich-type MnMoO4@NiMoO4@Mn2O3 core-shell nanostructured materials and their application in the high-performance battery-supercapacitor hybrid devices

We synthesized the sandwich-type of MnMoO4@NiMoO4@Mn2O3 core-shell nanosheet arrays (MMNM) that were grown on nickel foams (NFs) via a two-step controllable hydrothermal reaction. Compared with the previously reported core-shell materials, the structure of MMNM series materials was more unique and abundant, and its application prospect was extremely broad. The electrochemical properties of the prepared electrodes were tested in a three-electrode system, among which the MMNM-2 electrode exhibited the best electrochemical performance. The battery-supercapacitor hybrid device (MMNM-2 //AC BSH device) fabricated with MMNM-2 and activated carbon (AC) as the positive electrode and the negative electrode, respectively, achieved a high energy density of 49.99 W h kg−1 at a power density of 877.87 W kg−1. Moreover, the MMNM-2//AC BSH device exhibited better cycling stability than most previously reported BSH devices, with a high capacity retention of 96.03% after 20,000 cycles at a current density of 10 mA cm−2. The excellent electrochemical performance indicated the potential application of MMNM-2 in new energy storage devices.