Figure - available from: Journal of Solid State Electrochemistry
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(a–d) SEM images the NiCo2O4–900 nanosheet arrays on Ni foam with different magnifications. The inset shows the cross-section magnified image of (b)
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To achieve high-performance supercapacitors, electrode materials with the accessible electrode area, electrons, and ions diffusion channels are strongly needed. Herein, the network-like holey NiCo2O4 nanosheet arrays grown on Ni foam have been synthesized by a facile and efficient electrodeposition followed by calcination as a binder-free electrode...
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3D transition metal oxides, especially constructed from the interconnected nanowires directly grown on conductive current collectors, are considered to be the most promising electrode material candidates for advanced supercapacitors because 3D network could simultaneously enhance the mechanical and electrochemical performance. The work about design...
We report the synthesis of manganese-doped nickel cobalt oxide (Mn-doped NiCo2O4) nanoparticles (NPs) by an efficient hydrothermal and subsequent calcination route. The material exhibits a homogeneous distribution of Mn dopants and a battery-type behavior when tested as a supercapacitor electrode material. Mn-doped NiCo2O4 NPs show an excellent spe...
Bi2O3 nanoparticles coupled with reduced graphene oxide (rGO) nanostructure were synthesized through liquid-phase precipitation and calcination method, and their supercapacitor properties were studied as negative electrode materials. The as-prepared Bi2O3/rGO achieved a maximum specific capacitance of 1423 F g−1 at a current density of 1 A g−1, exc...
A special gas-phase diffusion precipitation method with ammonia as the gas-phase diffusion precipitant was adopted. After fully reacting with different cobalt sources in a sealed space, the liquid funnel was separated and dried, and calcined at different temperatures for 2 h. The prepared Co3O4 powder was used as a supercapacitor (SCs) electrode to...
Citations
... The electronic state of the elements in the NiCo2O4 film was analyzed by XPS ( Figure 10). According to the data obtained, the experimental curves of cobalt Co2p and nickel Ni2p are similar to the results of Ref [71]. At the first stage, the spectra of nickel and cobalt were fitted without determining the elements states (Figure 10a,b). ...
... The electronic state of the elements in the NiCo 2 O 4 film was analyzed by XPS ( Figure 10). According to the data obtained, the experimental curves of cobalt Co2p and nickel Ni2p are similar to the results of Ref [71]. At the first stage, the spectra of nickel and cobalt were fitted without determining the elements states (Figure 10a,b). ...
Using a combination of chemical coprecipitation and hydrothermal treatment of the resulting dispersed system, a hierarchically organized NiCo2O4 nanopowder was obtained, consisting of slightly elongated initial oxide nanoparticles self-organized into nanosheets about 10 nm thick, which in turn are combined into hierarchical cellular agglomerates of about 2 μm. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HR-TEM) allowed to confirm the formation of NiCo2O4 powder with the desired crystal structure via additional heat treatment of the intermediate product. Energy-dispersive X-ray spectroscopy (EDX) was used to confirm the target metal ratio, and the uniform distribution of the elements (Ni, Co and O) was shown by mapping. The resulting nanopowder was employed to prepare functional inks suitable for microplotter printing of the NiCo2O4 film. It was found that an oxide film morphology is fully inherited from the hierarchically organized oxide nanopowder used. Atomic force microscopy (AFM) revealed the film thickness (15 μm) and determined the maximum height difference of 500 nm over an area of 25 μm2. Kelvin probe force microscopy (KPFM) showed that the surface potential was shifted to the depths of the oxide film, and the work function value of the material surface was 4.54 eV, which is significantly lower compared to those reported in the literature. The electronic state of the elements in the NiCo2O4 film under study was analyzed by X-ray photoelectron spectroscopy (XPS). Chemosensor measurements showed that the printed receptor layer exhibited selectivity and high signal reproducibility for ethanol detection. As the relative humidity increases from 0 to 75%, the response value is reduced; however, the sensor response profile and signal-to-noise ratio remain without significant changes.
... The narrow scan spectrum of Co 2p is shown in Fig. 6c, the peaks at 779.3 and 794.8 eV were assigned to the Co 3? phase, the other fitted binding energies at 782.3 and 796.5 eV were assigned to the Co 2? phase. Simultaneously, two satellite peaks at 789 eV and [27][28][29]. The fitted Ni 2p spectrum is displayed in Fig. 6d, the peaks located at 854.6 and 871.3 eV were ascribed to Ni 3? , the peaks at 856.1 and 875 eV were corresponded to Ni 2? . ...
The rapid development of wearable and portable smart equipment has led to a research boom in flexible energy storage devices. Herein, NiCo2O4 nanosheet arrays have been successfully grown on carbon fibers (CFs), which was firstly modified by the three-dimensional Ni (3D-Ni) to repair the cracks and grooves in the surface of CF. The obtained CFs@3D-Ni/NiCo2O4 electrode possesses a high specific capacity of 736 F/g at 1 A/g current density in the three-electrode system. More importantly, the composite showed excellent electrochemistry stability after temperature plummets. The all-solid-state asymmetric supercapacitor device (ASC) assembled by CFs@3D-Ni/NiCo2O4 delivers a wonderful specific capacity of 176 F/g, a high energy density 55 W h/Kg at 750 W/Kg, excellent cycling stability (about 97.84% after 2000 cycles), and high flexibility (almost no influence in electrical performance at various bending angles). This work has provided a promising method to prepare high performance of the flexible and lightweight energy storage equipment.
... Copyright © 2013 Elsevier Ltd.(ERGO) which itself was deposited on nickel-nickel oxide foam.In addition to these, NiCo 2 O 4 architectures of versatile morphologies have been electrochemically deposited on a variety of conducting surfaces. Some of these include honeycomb-shaped NiCo 2 O 4 on carbon cloth[174], ultrathin NiCo 2 O 4 nanosheets on three-dimensional interwoven nitrogen-doped carbon nanotubes[175], ultrathin porous NiCo 2 O 4 nanosheet arrays on flexible carbon fabric, 3D vertically aligned carbon nanotubes/NiCo 2 O 4 core/shell structures[176], hybrid composite Ni(OH) 2 @NiCo 2 O 4 on carbon fiber paper[177], 3D hierarchical NiCo 2 O 4 @MnO 2 hybrid nanomaterial on stainless steel mesh[178], freestanding bowl-like NiCo 2 O 4 on carbon fiber paper[179], network-like holey NiCo 2 O 4 nanosheet arrays on Ni foam[180], NiCo 2 O 4 @ carbon nanofibers ...
Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity, selectivity, wide concentration range, low detection limits, and excellent recyclability. Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area, high permeability, short electron, and ion diffusion pathways. Because of the rapid development of non-enzyme biosensors, the current state of methods for synthesis of pure and composite/hybrid NiCo2O4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein. Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies. Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides, viz. NiO and Co3O4, is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+ (0.58 V/0.49 V) and Co3+/Co2+ (0.53 V/0.51 V). Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene, reduced graphene oxide, carbon nanotubes (single and multi-walled), carbon nanofibers; conducting polymers like polypyrrole (PPy), polyaniline (PANI); metal oxides NiO, Co3O4, SnO2, MnO2; and metals like Au, Pd, etc. Various factors affecting the morphologies and biosensing parameters of the nano-/micro-structured NiCo2O4 are also highlighted. Finally, some drawbacks and future perspectives related to this promising field are outlined.
... The electrode performance of 2D nanosheets can be further improved by the formation of surface holes by the maximization of ion diffusion and contact with the electrolyte. Various holey 2D nanosheets with good electrode performance for supercapacitors as well as metal ion and metal-O 2 secondary batteries have been reported [35][36][37]. Another merit of inorganic nanosheets is the surface exposure of a large number of redoxable ions with tunable compositions. ...
Exfoliated two-dimensional (2D) nanosheets of inorganic solids exhibit various unique characteristics such as unusually high morphological and structural anisotropy, great diversity in composition and structure, and tunable physicochemical properties. The large 2D surface area and high electrochemical activity of inorganic nanosheets render them as potential materials for supercapacitor electrodes. The electrode performance of these nanosheets can be further improved by their hybridization with highly conductive and/or electrochemically active species. This review focuses on the application of 2D inorganic nanosheets as supercapacitor electrodes and versatile building blocks for synthesizing novel hybrid electrode materials. The crucial roles of 2D inorganic nanosheets in high-performance electrode materials for supercapacitors are discussed and several intriguing examples of 2D inorganic nanosheet-based electrode materials have also been provided. The perspective for future research in this field is discussed along with various strategies to optimize the electrode performance of 2D inorganic nanosheet-based hybrid materials.
The globe is currently dealing with serious issues related to the world economy and population expansion, which has led to a significant increase in the need for energy. One of the most promising energy devices for the next generation of energy technology is the supercapacitor (SC). Among the numerous nanostructured materials examined for SC electrodes, inorganic nanosheets are considered to be the most favorable electrode materials because of their excellent electrochemical performance due to their large surface area, very low layer thickness, and tunable diverse composition. Various inorganic nanosheets (NS) such as metal oxides, metal chalcogenides, metal hydroxides, and MXenes show substantial electrochemical activity. Herein, a comprehensive survey of inorganic NS arrays synthesized through the electrodeposition method is reported with the discussion on detailed growth mechanism and their application in the fabrication of SC electrodes/devices for powering flexible and wearable electronics appliances. To begin with, the first section will feature the various types of electrodeposition working mechanism, SC types and their working mechanisms, importance of nanosheet structure for SCs. This review gives a profound interpretation of supercapacitor electrode materials and their performances in different domains. Finally, a perspective on NS array through electrodeposition method applications in diverse fields is extensively examined.
To enhance the capacitance of an inorganic electrode material, CoFe-layered double hydroxide (LDH) was grafted on the surface of hexagonal-flower-like NiCo2O4. Composites with different Co/Fe ratios were directly grown on Ni foam by using the hydrothermal method. The composite with the Co/Fe molar ratio of 1:2 (NiCo2O4 @Co1Fe2-LDH) exhibited the best electrochemical performance, with a specific capacitance of 2595 F g⁻¹ at a current density of 1 A g⁻¹. The composite prevented the aggregation of CoFe-LDH and induced reversible redox reactions, thus showing high specific capacitance and good stability. The application of the electrode on a packaging asymmetric capacitor consisting of NiCo2O4 @Co1Fe2-LDH as the anode, activated carbon as the cathode yielded a maximum energy density of 27.33 Wh kg⁻¹ at a power density of 800 W kg⁻¹ and an excellent capacitive retention of 96% even after 5000 charge-discharge cycles.
In this work, a one-step electrodeposition approach was applied for nanosheets fabrication of binder free nickel cobalt oxide (NCO) and NCO-reduced graphene oxide (NCO-rGO) composites on the nickel-foam substrate by repetitive cyclic voltammetry (rCV). The NCO-rGO hybrids were firstly fabricated on Ni foam surface with the reduction of GO and electrodeposition of NCO simultaneously. Interaction of NCO particles with rGO sheets increased the conductivity of the composite and consequently facilitated the electron transfer rate. Electrochemical measurements proved that specific capacitance and cyclic performance of as-prepared materials were improved with the synergistic effect of rGO in the hybrid structure. The optimized NCO-rGO electrode exhibited a specific capacitance of 1916.5 F g⁻¹ at 1 A g⁻¹ with superior stability of 95.6% at a high current density of 10 A g⁻¹ even after 3000 cycles. To explore its practical applications, an asymmetric supercapacitor (ASC) based on NCO-rGO as a positive electrode and rGO as a negative electrode was constructed, which exhibited a prominent specific energy of 45.22 Wh kg⁻¹ at 400 W kg⁻¹. As a result, NCO-rGO hybrid structure as the functional electrode material for the supercapacitors with remarkable electrochemical performance were obtained, thanks to the increased conductivity and decreased mass by removing binders.
