A unique core-shell structured ZnO/NiO heterojunction to improve the performance of supercapacitors produced using a chemical bath deposition approach.

The integration of metal oxide composite nanostructures has attracted great attention in supercapacitor (SC) applications. Herein, we fabricated a series of metal oxide composite nanostructures, including ZnO nanowires, NiO nanosheets, ZnO/CuO nanowire arrays, ZnO/FeO nanocrystals, ZnO/NiO nanosheets and ZnO/PbO nanotubes, via a simple and cost-effective chemical bath deposition (CBD) method. The electrochemical properties of the produced SCs were examined by performing cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) analysis, and electrochemical impedance spectroscopy (EIS). Of the different metal oxides and metal oxide composites tested, the unique surface morphology of the ZnO/NiO nanosheets most effectively increased the electron transfer rate and electrical conductivity, which resulted in improved energy storage properties. The binder-free ZnO/NiO electrode delivered a high specific capacitance/capacity of 1248 F g-1 (599 mA h g-1) at 8 mA cm-2 and long-term cycling stability over the course of 3000 cycles with a capacity retention of 79%. These results suggested a superiority in performance of the ZnO/NiO nanosheets relative to the nanowires, nanowire arrays, nanocrystals, and nanotubes. Thus, the present work has provided an opportunity to fabricate new metal oxide composite nanostructures with high-performance energy storage devices.

Selenium vacancies enriched the performance of supercapacitors with excellent cycling stability via a simple chemical bath deposition method.

Herein, we report a simple and cost-effective route for the fabrication of NiWO4, NiWO4P, and NiWO4Se nanostructures using the chemical bath deposition method. As a binder-free electrode material for pseudo capacitors (PCs), the fabricated nickel foam-supported NiWO4Se exhibited an excellent cycling life of 3000 cycles with a high specific capacitance of 1115.05 F g-1 at 20 mA cm-2. The desirable electrochemical performance of NiWO4Se was mainly attributed to the large specific area, short ion diffusion distance, and the introduction of selenium, which provide transport pathways for electrons and provide more active sites for electrochemical energy storage. The present simple and scalable synthesis shows great potential for the future development of transition metal selenides for different energy storage and conversion applications.

Facile synthesis of NF/ZnOx and NF/CoOx nanostructures for high performance supercapacitor electrode materials.

NF/ZnOx nanocone and NF/CoOx nanoparticle electrode materials were fabricated on a nickel foam surface using a simple chemical bath deposition approach and assessed as an electrode material for high-performance supercapacitors (SCs). The electrochemical properties of the NF/ZnOx and NF/CoOx electrodes were examined by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy. The fabricated NF/ZnOx and NF/CoOx SCs devices exhibited a good specific capacitance of 2437 and 2142 F g-1 at a current density of 20 mA g-1, respectively, in a three electrode system. Furthermore, the NF/ZnOx and NF/CoOx electrode materials showed acceptable long cycle-life stability with 97.8% and 95.8% specific capacitance retention after 3000 cycles at a current density of 22 mA g-1 in a 2 M aqueous KOH solution. Furthermore, the NF/ZnOx and NF/CoOx SCs showed a high energy density of 54.15 W h kg-1 and 47.6 W h kg-1 at a power density of 499.8 W kg-1 and 571.2 W kg-1, respectively, with maximum operating voltage of 0.5 V. Overall, NF/ZnOx and NF/CoOx electrode materials are promising electrodes for electrochemical energy storage applications.