3D hierarchical CoFe2O4/CoOOH nanowire arrays on Ni-Sponge for high-performance flexible supercapacitors

Hierarchical construction of 3D binder-free NiMoO4/CoFe2O4/NF arrays to enhance water splitting and charge-storage efficiency

Developing inexpensive, highly active, robust bi-functional electrocatalysts for energy conversion and storage technology remains a vital challenge. Herein, we hierarchically constructed 3D binder-free NiMoO4/CoFe2O4/NF heterostructure material via an effective and facile two-step hydrothermal process. The strong electronic coupling among NiMoO4 and CoFe2O4 counterparts alternates the charge environment at the NiMoO4/CoFe2O4 interface, which builds the highway for a rapid and continuous charge transfer process. According to the surface characterization data, the 3D NiMoO4/CoFe2O4/NF surface possesses numerous multivalent active sites and affords robust structural and chemical stability to the electrode material. Benefiting from the hierarchical morphological reconstruction and synergistic effect between two functional materials of NiMoO4/CoFe2O4/NF heterostructure attained excellent over potential values of 88 mV and 249 mV with minimal Tafel slope value of 73 mV dec-1, 84 mV dec-1 for HER and OER respectively. For overall water splitting, experimental results demonstrated splendid stability over 50 h with a small cell voltage of 1.56 V at a current density of 10 mA cm-2 in a 1 M KOH alkaline electrolyzer. Furthermore, its specific capacitance (CS) reached 811C g-1 at 1 A/g and retained 85.5 % cycling stability after 5000 cycles at a current density of 5 A/g in a 6 M KOH electrolyte medium. This bi-functional hierarchical NiMoO4/CoFe2O4/NF heterostructured assembly will render outstanding electrocatalytic activity for future sustainable energy conversion and storage systems.

Construction of Ternary Zn0.5Cu0.5Co2O4 Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High-Energy-Density Asymmetric Supercapacitor Application

Developing nanostructured multi-transition metal-based spinel architectures represents a strategic approach for boosting the energy density of supercapacitors while preserving high power density. Here, the influence of incorporating Zn and Cu into Co3O4 spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, Co3O4), binary (ZnCo2O4, CuCo2O4), and ternary (Zn0.5Cu0.5Co2O4) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower-like structures of Zn0.5Cu0.5Co2O4, comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics. Oxygen vacancies induced defect states in Zn0.5Cu0.5Co2O4, shifting the d- and p-band center values closer to the Fermi level and enhancing electrochemical performance. The Zn0.5Cu0.5Co2O4 exhibits a specific capacity of 271 mA h g-1 (1776 F g-1) at 1 A g-1 with 97% capacity retention after 5 000 charge/discharge cycles. In a Zn0.5Cu0.5Co2O4//activated carbon configuration, the device demonstrates superior energy and power densities of 122.2 Wh kg-1 and 800 W kg-1, respectively, maintaining 91% capacitance after 10 000 cycles at 30 A g-1 with high coulombic efficiency. This study presents an effective strategy to enhance ion/charge transfer and adsorption in multi-transition metal spinel architectures, advancing the development of supercapacitor electrodes.

Fabrication of composite GO/NiFe2O4-MnFe2O4-CoFe2O4 anode material: Toward high performance hybrid supercapacitors

Here, NiFe2O4, MnFe2O4, and CoFe2O4 nanoferrites are prepared by coprecipitation synthesis technique from nickel, manganese, and cobalt chloride precursors. Synthesized nanoferrites are annealed by calcination process at 800°C for 2 h. To produce a novel anode electrode material for asymmetric supercapacitors (ASCs), the composite material of GO/NiFe2O4-MnFe2O4-CoFe2O4 is fabricated. Physicochemical aspects of the synthesized nanoferrites are evaluated. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy tests are conducted, respectively. The electrochemical activities are studied by cyclic voltammetry, glavanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) in 2 M KOH as the electrolyte. In three electrode system, the novel GO/NiFe2O4-MnFe2O4-CoFe2O4 electrode displays a high specific capacity of 325 C g-1 and preserves about 99.9% of its initial specific capacity. The GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs device is assembled using GO/NiFe2O4-MnFe2O4-CoFe2O4, GO, and 2 M KOH solution as the positive electrode, negative electrode, and electrolyte, respectively. Significantly, the GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs represent an outstanding energy density of 50.5 W h kg-1 at power density of 2560 W kg-1. Through the long-term charge discharge cycling tests, this ASC device illustrates about 93.7% capacity retention after 3000 cycles. Then, the present study provides the NiFe2O4-MnFe2O4-CoFe2O4 composite nanoferrites as a novel favorable candidate for anode material. RESEARCH HIGHLIGHTS: Simple and green synthesis of magnetic NiCo2O4/NiO/rGO composite nanostructure using natural precursor. Fabricating and designing an efficient semiconductor for degradation ability. NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The photocatalytic performance of NiCo2O4/NiO/rGO was surveyed for the degradation of various antibiotics below visible radiation. Efficiency was 92.9% to eliminate tetracycline. We developed a synergetic approach to prepare a novel active material composed of GO/ NiFe2O4-MnFe2O4-CoFe2O4 by a hybrid electrode material. Green synthesis method was accomplished to attain NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The oxide nanobundles were prepared with a rapid and eco-friendly method. In order to investigation of the effect of natural precursor, morphology and shape of nanoproducts was compared. NiCo2O4/NiO/rGO nanobundles possess a suitable bandgap in the visible area.

Construction and application of NiCo2O4@MnS composite with hierarchical structure for hybrid supercapacitor

The development of an electrochemical energy storage system with exceptional performance is an important way to address the energy crisis and environmental pollution of the modem world. In this study, an NiCo2O4@MnS composite with a unique hierarchical structure has been successfully synthesized on an NF substrate using the hydrothermal-electrodeposition method. The results indicate that NiCo2O4@MnS possesses superior specific capacitance and excellent cycling stability. At a current density of 2 A g-1, its specific capacitance can reach 2100 F g-1, while the capacitance retention is still 76% after 10 000 cycles at 10 A g-1. Moreover, when the current density is 1 A g-1, the assembled NiCo2O4@MnS//AC device can deliver a specific capacitance of 203 F g-1, and the energy density is up to 55 W h kg-1 at a power density of 697 W kg-1. These outstanding electrochemical properties of NiCo2O4@MnS can be ascribed to the increase in ion diffusion, specific surface area and electronic conductivity due to its unique hierarchical structure and introduction of MnS.

Effects of chemical composition and vacant oxygen defects on the performance of Ni(OH)2–Ni0.85Se heterostructure nanowires as supercapacitor electrodes

The research focus of supercapacitors is the composition and structural design of electrode materials.

CoFe2O4 Hollow Spheres-Decorated Three-Dimensional rGO Sponge for Highly Efficient Electrochemical Charge Storage Devices

The energy demand, the crisis of fossil fuels, and the increasing popularity of portable and wearable electronics in the global market have triggered the demand to develop high-performance flexible all-solid-state supercapacitors that are capable of delivering high energy at high power density as well as being safely entrenched in those electronics. Herein, we have designed a nanocomposite, 80CFhs-20rGOsp, which exhibits a high specific capacitance (C S) value of 1032 F g-1 at 3 A g-1. Utilizing this nanocomposite as the cathode and reduced graphene oxide sponge (rGOsp) as the anode, a flexible all-solid-state asymmetric device has been fabricated. In this device, poly(vinyl alcohol) (PVA) gel embedded with a mixture of 3 M KOH and 0.1 M K4[Fe(CN)6] was used as an electrolyte cum separator. The fabricated device showed the capability to deliver an energy density of 65.8 W h kg-1 at a power density of 1500 W kg-1 and retained its capability even after various physical deformations. The device also exhibited a long cycle life and retained ∼96% of its C S value after 5000 cycles. Moreover, the fabricated flexible all-solid-state device successfully illuminated light-emitting diodes, which proved its potential use in real-life supercapacitor applications. The obtained results revealed the excellent electrochemical performances of the fabricated device and rendered it a promising candidate in the energy sector.