Ni(OH)2 nanosheets grown on porous hybrid g-C3N4/RGO network as high performance supercapacitor electrode

Facile Synthesis of Sandwich-Type Porous Structured Ni(OH)2/NCNWs/rGO Composite for High Performance Supercapacitor

Nickel hydroxide has ultra-high energy storage capacity in supercapacitors, but poor electrical conductivity limits their further application. The use of graphene to improve its conductivity is an effective measure, but how to suppress the stacking of graphene and improve the overall performance of composite materials has become a new challenge. In this work, a well-designed substrate of N-doped carbon nanowires with reduced graphene oxide (NCNWs/rGO) was fabricated by growing polypyrrole (PPy) nanowires between GO nanosheets layers and then calcining them at high temperatures. This NCNWs/rGO substrate can effectively avoid the stacking of rGO nanosheets, and provides sufficient sites for the subsequent in situ growth of Ni(OH)2, forming a uniform and stable Ni(OH)2/NCNWs/rGO composite material. Benefiting from the abundant pores, high specific surface area (107.2 m2 g-1), and conductive network throughout the NCNWs/rGO substrate, the deposited Ni(OH)2 can not only realize an ultra-high loading ratio, but also exposes more active surfaces (221.3 m2 g-1). After a comprehensive electrochemical test, it was found that the Ni(OH)2/NCNWs/rGO positive materials have a high specific capacitance of 2016.6 F g-1 at a scan rate of 1 mV s-1, and exhibit significantly better stability. The assembled Ni(OH)2/NCNWs/rGO//AC asymmetric supercapacitor could achieve a high energy density of 85.2 Wh kg-1 at power densities of 381 W kg-1. In addition, the asymmetric supercapacitor has excellent stability and could retain 70.1% of initial capacitance after 10,000 cycles. These results demonstrate the feasibility of using NCNWs/rGO substrate to construct high-performance supercapacitor electrode materials, and it is also expected to be promoted in other active composite materials.

Hybrid TiO2-RGO nanocomposite as high specific capacitance electrode for supercapacitor

This study describes the fabrication of composite electrodes comprising TiO2and reduced graphene oxide layers using a moderate-temperature hydrothermal method. The morphology, crystalline structure, chemical composition, and optical features of the prepared composites were analyzed by FE-SEM, x-ray diffraction, FTIR, and UV-visible spectroscopy. The cyclic voltammetry (CV) and Nyquist plots were used to assess the electrochemical and impedance responses of the composite electrodes, respectively. The analysis revealed that the incorporation of RGO reduced the TiO2bandgap to 3.87 eV 3.02 eV and improved the specific capacitance, enhancing the TiO2-RGO electrode's supercapacitive performance. CV studies highlight that the TiO2-RGO composite has a high specific capacitance of 152 F g-1at a substantially faster scan rate of 25 mV s-1in a 1.0 M-KOH dilute electrolyte. These findings confirmed the applicability of the fabricated electrodes as prospective supercapacitor electrodes.

Extrinsic Pseudocapacitive NiSe/rGO/g-C3N4 Nanocomposite for High-Performance Hybrid Supercapacitors

Battery-type materials with ultrahigh energy density show great potential for hybrid supercapacitors (HSCs). In this work, we have developed a nickel selenide (NiSe)/reduced graphene oxide (rGO)/graphitic carbon nitride (g-C3N4) ternary composite as a promising positive electrode for hybrid supercapacitors (HSCs). The extended π-conjugated planar layers of g-C3N4 promote strong interconnectivity with rGO, which further enhances surface area, surface free energy, and efficient electron/ionic path. Additionally, it establishes clear ion diffusion pathways, serving as ion reservoirs during charge and discharge and facilitating efficient redox reactions. As a result, the NiSe/g-C3N4/rGO nanocomposite electrode displayed a specific capacity of 412.6 mA h g-1 at 1 A g-1. Later, the HSC device was assembled using the nanocomposite as the positive electrode and activated carbon as the negative electrode, which delivered an energy density of 65.2 Wh kg-1 at a power density of 750 W kg-1. Notably, the HSC device maintained excellent cyclic stability, preserving 93.3% of its initial performance and Coulombic efficiency of 86.6% for 10,000 charge-discharge cycles at 5 A g-1. These findings underscore the potential utility of NiSe/g-C3N4/rGO as a versatile and effective electrode material for the strategic development of HSC devices.

Designing of Carbon Nitride Supported ZnCo2O4 Hybrid Electrode for High-Performance Energy Storage Applications

This study reports a unique graphitic-C₃N₄ supported ZnCo₂O₄ composite, synthesized through a facile hydrothermal method to enhance the electrochemical performance of the electrode. The g-C₃N₄@ZnCo₂O₄ hybrid composite based electrode exhibits a significant increase in specific surface area and maximum specific capacity of 157 mAhg⁻¹ at 4 Ag⁻¹. Moreover, g-C₃N₄@ZnCo₂O₄ electrode maintained significant capacity retention of 90% up to 2500 cycles. Utilizing this composite in the development of the symmetric device, g-C₃N₄@ZnCo₂O₄//g-C₃N₄@ZnCo₂O₄ displays a specific capacity of 121 mAhg⁻¹. The device exhibits an energy density of 39 Whkg⁻¹ with an equivalent power density of 1478 Wkg⁻¹. A good cycling stability performance with an energy efficiency of 75% and capacity retention of 71% was observed up to 10,000 cycles. The superior performance of g-C₃N₄@ZnCo₂O₄ is attributed to the support of the g-C₃N₄ which increases the surface area, electroactive sites and provides chemical stability for electrochemical performance. The outstanding performance of this exclusive device symbolizes remarkable progress in the direction of high-performance energy storage applications.