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The development of asymmetric supercapacitors requires the design of electrode construction and the utilization of new electroactive materials. In this regard, an effective strategy is the loading of active materials on an integrated 3D porous graphene-based substrate such as graphene foam (GF). Herein, we successfully designed and fabricated a novel ternary binder-free nanocomposite consisting of polypyrrole, Fe–Co sulfide, and reduced graphene oxide on a nickel foam electrode (PPy/FeCoS-rGO/NF) via a facile, cost-effective, and powerful electrodeposition method for application in high-performance asymmetric supercapacitors. The monolithic 3D porous graphene foam (GF) obtained by the facile immersion method not only improves uniform growth of the FeCoS ultrathin porous nanosheet and conductive PPy film but also significantly boosts the mechanical stability, rate capability, and energy storage capacity. The results revealed that FeCoS interconnected nanosheets coated with a highly conductive PPy layer via the electrodeposition method are well decorated on the wrinkled surface of the graphene foam backbones. The PPy/FeCoS-rGO/NF exhibits excellent electrochemical performance with a high specific capacitance of 3178 F/g at 2 A/g and a good rate capability. The excellent electrochemical performance can be ascribed to the high surface area, superior electronic conductivity, low contact resistance between the PPy/FeCoS-rGO active layer and Ni foam current collector, short diffusion pathway for electrolyte ions, fast electron transfer, and effective utilization of active material during Faradaic charge-storage processes. Benefiting from their superior properties, a hybrid asymmetric supercapacitor is assembled by employing PPy/FeCoS-rGO/NF as the positive electrode and nickel foam coated with reduced graphene oxide (rGO/NF) as the negative electrode. Assembling the PPy/FeCoS-rGO//rGO device exhibits a high specific capacitance of 94 F/g at 1 A/g and an energy density of 28.3 Wh kg–1 at a power density of 810 W kg–1. Moreover, the asymmetric supercapacitor device shows an outstanding cycling performance with 97.5% capacitance retention after 2500 cycles. The obtained results demonstrate the PPy/FeCoS-rGO/NF electrode can be used as a promising electrode material for asymmetric supercapacitor applications.

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Flexible and lightweight fiber-shaped micro-supercapacitors have attracted tremendous attentions in the next-generation portable electronic devices, due to their high flexibility, tiny volume, and wearability. Herein, we successfully fabricated a ternary...

Miniaturization of electronic devices with portable, flexible and wearable characteristics created a great demand for high-performance microscale energy storage devices with lightweight and flexible properties. Among the energy storage devices, wire-shaped supercapacitors (WSSCs) have recently received tremendous attention due to their tiny volume, wearability, high flexibility and potential applications in the next-generation portable/wearable electronic devices. Herein, we successfully fabricated a porous dendritic Ni–Cu film on Cu wire substrate (CWE) for fabrication of high-performance wire-type supercapacitors. The porous structure with dendritic morphology provides a high surface area, short ion diffusion pathway and low contact resistance between electroactive materials and metal wire electrode. The Ni­(OH)2 electroactive material is then deposited on Ni–Cu/CWE. The fabricated Ni­(OH)2/Ni–Cu/CWE exhibits excellent electrochemical performances with high areal (volumetric and length) specific capacitance of 12.2 F cm–2 (1220.89 F cm–3, 1.53 F cm–1), respectively at a current density of 4 mA cm–2, and an excellent cycle stability (100% even after 3500 cycles). A novel fiber-shaped flexible asymmetric micro–supercapacitor (ASC) based on Ni­(OH)2/Ni–Cu/CW as positive electrode and reduced graphene oxide/carbon fiber (RGO/CF) as the binder free negative electrode was assembled. This device can be operated reversibly in the voltage range of 0–1.6 V and exhibited a maximum areal and volumetric energy (E A = 195 μWh cm–2, E V = 15.04 mWh cm–3) and power (P A = 7643 μW cm–2, P V = 588 mW cm–3) densities. In addition, the ASC device also exhibits an excellent cycling stability with 95.7% capacitance retention after 5000 cycles and good mechanical stability, which is checked by bending of the whole device at various angles. These promising results indicated the great potential of our fabricated device for portable, flexible and wearable applications.

A novel electrochemical sensor based on nanocellulose‐carbon nanoparticles (NC‐CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). Atomic force microscopy, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the roughness, surface morphology and performance of the deposited modifier film on GCE. SEM image demonstrated that modifier nanoparticles are uniformly deposited on GCE, with an average size of less than 50 nm. The electrochemical behavior of MCP and its oxidation product is studied using linear sweep and cyclic voltammetry over a wide pH range on NC‐CNPs modified glassy carbon electrode. The results revealed that the oxidation of MCP is an irreversible and pH‐dependent process that proceeds in an adsorption‐controlled mechanism and results in the formation of a main oxidation product, which adsorbs on the surface of NC‐CNPs/ GCE. The modified electrode showed a distinctive anodic response towards MCP with a considerable enhancement (49 fold) compared to the bare GCE. Under the optimized conditions, the modified electrode exhibited a wide linear dynamic range of 0.06–2.00 µM with a detection limit of 6 nM for the voltammetric determination of MCP. The prepared modified electrode showed several advantages such as simple preparation method, high stability, reproducibility, and repetitive usability. The modified electrode is successfully applied for the accurate determination of trace amounts of MCP in pharmaceutical and clinical preparations.

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Demand increasing for next generation portable and miniaturized electronics has aroused much interest to explore microscale and lightweight energy storage devices. Herein, we demonstrate successful development of flexible wire-shaped microsupercapacitors (micro-SCs) based on novel CoNi 2 S 4 /E-NZP film@Cu wire electrode. The etched Ni−Zn−P (E-NZP) film was synthesized by directly deposition of NZP film on Cu wire, followed by a chemical etching process. Alkaline etching treatment provides a micro-and mesoporous structure with high surface area and facilitates the penetration of electrolyte ions into the electrode matrix. Then, CoNi 2 S 4 nanosheets as electroactive material are electrochemically grown onto the E-NZP film@CW electrode under a constant potential. The synergistic effects contributed by various components inside the CoNi 2 S 4 /E-NZP@CW electrode deliver superior performances with a high specific capacitance of 1.12 F cm −1 , 8.9 F cm −2 , and 889.68 F cm −3 at 4 mA cm −2 , outstanding rate capability (0.66 F cm −1 , 5.3 F cm −2 , and 529.02 F cm −3 at 80 mA cm −2 ) and long-term cycling stability (93.4% capacitance retention after 7000 cycles). Moreover, a flexible solid-state asymmetric micro-SC is fabricated using CoNi 2 S 4 /E-NZP film @CW as the positive electrode and rGO-coated carbon fiber (rGO/CF) as the negative electrode. The fabricated device exhibits high length, areal and volumetric capacitances of C L : 40 mF cm −1 , C A : 0.241 F cm −2 and C V : 18.54 F cm −3 , good mechanical stability with a maximum energy (E L , 18 μW h cm −1 ; E A , 108.4 μW h cm −2 ; and E V , 8.34 mW h cm −3 ), and power densities (P L , 1454 μW cm −1 ; P A , 9280 μW cm −2 ; and P V , 716.9 mW cm −3 ). This work provides a new and facile approach to develop high-performance wire-shaped electrodes as a new generation in energy storage applications.