Binder-free 2D nanosheet Ni3V2O8/Ni-foam (NVO/Ni) and Ni3V2O8 (NVO) nanoparticles were synthesized using a facile hydrothermal technique for electrochemical capacitor applications. Both the NVO and NVO/Ni samples, produced using 1 M LiOH as a reducing agent during the synthesis, belong to the Ni3V2O8 phase. The electrochemical traits of these electrodes revealed that the NVO/Ni electrodes performed significantly better than the 3D NVO electrodes. The NVO/Ni electrode provided a specific capacitance of 1300 F/g at a current density of 1 A/g with high cycling stability (80.62% at 4 A/g) after 7000 cycles due to structural advantages. Moreover, the NVO/Ni//AC asymmetric supercapacitor device delivered a high energy density of 33.2 Wh/kg at a power density of 2.4 kW/kg and high cycling stability over 10,000 cycles in the 1.2 V working potential window. The device also showed a considerably high maximum power density of 7.2 kW/kg at a 13.62 Wh/kg energy density and remained stable even after 10,000 cycles. The energy–power performance depicted nearly 200% power gain over a mere 59% energy expense, indicating its potential applications in practical devices.

To meet the demand for the development of high energy storage devices, appropriate designs of advanced carbon nanostructures (CNs) with metal oxides are highly preferred. Herein, the surfaces of two advanced carbon nanostructures (CNs), g-C3N4 and carbon nanofibers, were modified by the addition of carboxyl functional groups and then bound to TiO2 nanospheres (TNS). The surface functionalization of CNs is an efficient approach for improving the performance of carbon-based supercapacitors by solving the dispersion problems. Field emission scanning electron microscopy and transmission electron microscopy images demonstrated the sheet, fiber, and sphere morphologies of g-C3N4, carbon, and TiO2, respectively. According to the results of Fourier transform infrared spectroscopy, the carboxyl functional groups with CNs were confirmed. In a three-electrode system, the supercapacitance of fictitious electrodes was evaluated with a 4 M KOH electrolyte. The surface-functionalized hybrid electrode showed a specific capacitance (817 F g–1) at a current density of 0.25 A g–1 superior to those of the other fictitious electrodes. The electrode showed stability for up to 2000 cycles, with 89.2% capacitance retention. The superior electrochemical properties of CNs–TNS were attributed to the synergetic effects of g-C3N4–CNF/TiO2 composition and its excellent accessibility, conductivity, surface functionalization, and strong chemical interface. This study positively encourages the manufacture and design of carbon nanostructure based metal oxide nanostructures for high-performance supercapacitor applications.

Herein, we present an interfacial engineering strategy to construct an efficient hydrothermal approach by in situ growing cobalt-doped@MnO2 nanocomposite on highly conductive nickel foam (Ni foam) for supercapacitors (SCs). The remarkably high specific surface area of Co dopant provides a larger contacting area for MnO2. In the meantime, the excellent retentions of the hierarchical phase-based pore architecture of the cobalt-doped surface could beneficially condense the electron transportation pathways. In addition, the nickel foam (Ni foam) nanosheets provide charge-transport channels that lead to the outstanding improved electrochemical activities of cobalt-doped@MnO2. The unique cobalt-doped@MnO2 nanocomposite electrode facilitates stable electrochemical architecture, multi-active electrochemical sites, and rapid electro-transports channels; which act as a key factor in enhancing the specific capacitances, stability, and rate capacities. As a result, the cobalt-doped@MnO2 nanocomposite electrode delivered superior electrochemical activities with a specific capacitance of 337.8 F g–1 at 0.5 A g–1; this is greater than pristine MnO2 (277.9 F g–1). The results demonstrate a worthy approach for the designing of high-performance SCs by the grouping of the nanostructured dopant material and metal oxides.

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Tin monoselenide (SnSe) nanoparticles (NPs) have great potential to replace the conventional absorbers used in the fabrication of thin film solar cells.