Synergistic effect of microwave heating and hydrothermal methods on synthesized Ni2CoS4/GO for ultrahigh capacity supercapacitors

Facile syntheses of Fe2O3-rGO and NiCo-LDH-rGO nanocomposites for high-performance electrochemical capacitors

Faraday-type electrode materials and devices for electrochemical capacitors have been widely investigated. However, their applications are severely limited by the preparation method and cost of electrode materials. In this work, high-performance electrochemical capacitors were successfully assembled using Fe₂O₃-decorated reduced graphene oxide (rGO) nanocomposites and NiCo-Layered Double Hydroxides (LDH) as the anode and cathode, respectively. An easy and efficient approach (the modified precipitation method) for the large-scale fabrication was used to prepare Fe₂O₃ and NiCo-LDH, supported by rGO sheets, respectively. The anode material, Fe₂O₃-rGO, exhibited an excellent specific capacitance (C_sp) of 1073 F g^-1 at a current density of 1 A g^-1 and a retention rate of 92 % at 10 A g^-1, while the NiCo-LDH-rGO cathode material provided a C_sp of 1850 F g^-1 at 1 A g^-1 and maintained 84 % at 10 A g^-1. The effective combination of these electrodes for the NiCo-LDH-rGO//Fe₂O₃-rGO electrochemical capacitors resulted in an excellent energy density of 108 Wh/kg at a power density of 884 W/kg, with remarkable cycling stability (80 % after 1000 cycles at 10 A g^-1). We believe that this work, including the proposed method and electrode materials, will advance the further development and commercialization of electrochemical capacitors.

High-performance flexible supercapacitor enabled by Polypyrrole-coated NiCoP@CNT electrode for wearable devices

As a pseudocapacitive electrode material, nickel-cobalt bimetallic phosphide has attracted wide attention with its advantage in capacitance and chemical activity. While, like Ni-Co oxides or sulfides, the application of nickel-cobalt bimetallic phosphide is generally hampered by its confined conductivity, low chemical stability and unsatisfactory cycle durability. Herein, this work demonstrates a NiCoP@CNT@PPy (NCP@CNT@PPy) composite that is obtained by polymerizing pyrrole monomer on the surface of NiCoP@CNT complex. According to density functional theory (DFT), it is theoretically demonstrated that the bimetallic Ni-Co phosphide (NiCoP) can exhibit more electrons near the Fermi level than single Ni or Co phosphide. Under the combined effects of carboxylic carbon nanotubes (c-CNTs) and polypyrrole (PPy), the NCP@CNT@PPy electrode exhibits excellent electrochemical performance. In addition, a flexible asymmetric supercapacitor (ASC) is prepared, which demonstrated high energy density and admirable heat-resistance and flexibility performance, showing huge potential in the application of heat-resistant storage energy systems and portable wearable devices.

Microwave heating followed by a solvothermal method to synthesize nickel–cobalt selenide/rGO for high-performance supercapacitors

Efficient microwave heating followed by a solvothermal method is used to synthesize (Ni0.85Se)3(Co0.85Se)/rGO nanorods with an ultrahigh specific capacitance of 2009 F g−1 at a current density of 2 A g−1.

A review of the microwave-assisted synthesis of carbon nanomaterials, metal oxides/hydroxides and their composites for energy storage applications

Currently, nanomaterials are considered to be the backbone of modern civilization. Especially in the energy sector, nanomaterials (mainly, carbon- and metal oxide/hydroxide-based nanomaterials) have contributed significantly. Among the various green approaches for the synthesis of these nanomaterials, the microwave-assisted approach has attracted significant research interest worldwide. In this context, it is noteworthy to mention that because of their enhanced surface area, high conducting nature, and excellent electrical and electrochemical properties, carbon nanomaterials are being extensively utilized as efficient electrode materials for both supercapacitors and secondary batteries. In this review article, we briefly demonstrate the characteristics of microwave-synthesized nanomaterials for next-generation energy storage devices. Starting with the basics of microwave heating, herein, we illustrate the past and present status of microwave chemistry for energy-related applications, and finally present a brief outlook and concluding remarks. We hope that this review article will positively convey new insights for the microwave synthesis of nanomaterials for energy storage applications.

Microwave hydrothermal fabrication of 3D hierarchical Br/Bi2WO6 with enhanced photocatalytic activity for Rhodamine B and tetracycline degradation

Basing on the unique advantages of uniform and rapid volumetric heating of microwave irradiation, microwave hydrothermal method has been used to fabricate Br/Bi₂WO₆ for streamlining the preparation procedure and enhancing the photocatalytic activity. The results indicated that Br was successfully introduced into the lattice of Bi₂WO₆, which improved the absorption ability of visible light. Moreover, Br/Bi₂WO₆ exhibited smaller size and the enhanced separation efficiency of photogenerated carriers as compared with Bi₂WO₆. Br/Bi₂WO₆ exhibited superior reusability and photocatalytic activity of Rhodamine B (RhB) and tetracycline (TC). Furthermore, the enhanced photocatalytic activity of Br/Bi₂WO₆ was mainly ascribed to the increased specific surface area, wide UV-vis light absorption range, and high separation efficiency of photogenerated charge carriers originating from Br doping and microwave heating.

Synergistic effects of Fe and Mn dual-doping in Co3S4 ultrathin nanosheets for high-performance hybrid supercapacitors

Dopant engineering in nanostructured materials is an effective strategy to enhance electrochemical performances via regulating the electronic structures and achieving more active sites. In this work, a robust electrode based on Fe and Mn co-doped Co₃S₄ (FM-Co₃S₄) ultrathin nanosheet arrays (NSAs) on the Ni foam substrate is prepared through a facile hydrothermal method followed by a subsequent sulfurization reaction. It has been found that the incorporation of Fe ions is beneficial to higher specific capacity of the final electrode and Mn ions contribute to the excellent rate capability in the reversible redox processes. Density functional theory (DFT) calculations further verify that the Mn doping in the Co₃S₄ obviously shorten the energy gap of Co₃S₄, which favors the electrochemical performances. Due to the synergetic effects of different transition metal ions, the as-prepared FM-Co₃S₄ ultrathin NSAs exhibit a high specific capacity of 390 mAh g^-1 at 5 A g^-1, as well as superior rate capability and excellent cycling stability. Moreover, the corresponding quasi-solid-state hybrid supercapacitors constructed with the FM-Co₃S₄ ultrathin NSAs and active carbon exhibit a high energy density of 55 Wh kg^-1 at the power density of 752 W kg^-1. These findings demonstrate a new platform for developing high-performance electrodes for energy storage applications.