A Facile Two-Step Hydrothermal Synthesis of Co(OH)2@NiCo2O4 Nanosheet Nanocomposites for Supercapacitor Electrodes

The composites of NiCo₂O₄ with unique structures were substantially investigated as promising electrodes. In this study, the unique structured nanosheets anchored on nickel foam (Ni foam) were prepared under the hydrothermal technique of NiCo₂O₄ and subsequent preparation of Co(OH)₂. The Co(OH)₂@NiCo₂O₄ nanosheet composite has demonstrated higher specific capacitances owing to its excellent specific surface region, enhanced rate properties, and outstanding electrical conductivities. Moreover, the electrochemical properties were analyzed in a three-electrode configuration to study the sample material. The as-designed Co(OH)₂@NiCo₂O₄ nanosheet achieves higher specific capacitances of 1308 F·g^-1 at 0.5 A·g^-1 and notable long cycles with 92.83% capacity retention over 6000 cycles. The Co(OH)₂@NiCo₂O₄ nanosheet electrode exhibits a long life span and high capacitances compared with the NiCo₂O₄ and Co(OH)₂ electrodes, respectively. These outstanding electrochemical properties are mainly because of their porous construction and the synergistic effects between NiCo₂O₄ and Co(OH)₂. Such unique Co(OH)₂@NiCo₂O₄ nanosheets not only display promising applications in renewable storage but also reiterate to scientists of the unlimited potential of high-performance materials.

Facile Synthesis of Battery-Type CuMn2O4 Nanosheet Arrays on Ni Foam as an Efficient Binder-Free Electrode Material for High-Rate Supercapacitors

The development of battery-type electrode materials with hierarchical nanostructures has recently gained considerable attention in high-rate hybrid supercapacitors. For the first time, in the present study novel hierarchical CuMn₂O₄ nanosheet arrays (NSAs) nanostructures are developed using a one-step hydrothermal route on a nickel foam substrate and utilized as an enhanced battery-type electrode material for supercapacitors without the need of binders or conducting polymer additives. X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques are used to study the phase, structural, and morphological characteristics of the CuMn₂O₄ electrode. SEM and TEM studies show that CuMn₂O₄ exhibits a nanosheet array morphology. According to the electrochemical data, CuMn₂O₄ NSAs give a Faradic battery-type redox activity that differs from the behavior of carbon-related materials (such as activated carbon, reduced graphene oxide, graphene, etc.). The battery-type CuMn₂O₄ NSAs electrode showed an excellent specific capacity of 125.56 mA h g^-1 at 1 A g^-1 with a remarkable rate capability of 84.1%, superb cycling stability of 92.15% over 5000 cycles, good mechanical stability and flexibility, and low internal resistance at the interface of electrode and electrolyte. Due to their excellent electrochemical properties, high-performance CuMn₂O₄ NSAs-like structures are prospective battery-type electrodes for high-rate supercapacitors.

Recent Advancements of Polyaniline/Metal Organic Framework (PANI/MOF) Composite Electrodes for Supercapacitor Applications: A Critical Review

Supercapacitors (SCs), also known as ultracapacitors, should be one of the most promising contenders for meeting the needs of human viable growth owing to their advantages: for example, excellent capacitance and rate efficiency, extended durability, and cheap materials price. Supercapacitor research on electrode materials is significant because it plays a vital part in the performance of SCs. Polyaniline (PANI) is an exceptional candidate for energy-storage applications owing to its tunable structure, multiple oxidation/reduction reactions, cheap price, environmental stability, and ease of handling. With their exceptional morphology, suitable functional linkers, metal sites, and high specific surface area, metal–organic frameworks (MOFs) are outstanding materials for electrodes fabrication in electrochemical energy storage systems. The combination of PANI and MOF (PANI/MOF composites) as electrode materials demonstrates additional benefits, which are worthy of exploration. The positive impacts of the two various electrode materials can improve the resultant electrochemical performances. Recently, these kinds of conducting polymers with MOFs composites are predicted to become the next-generation electrode materials for the development of efficient and well-organized SCs. The recent achievements in the use of PANI/MOFs-based electrode materials for supercapacitor applications are critically reviewed in this paper. Furthermore, we discuss the existing issues with PANI/MOF composites and their analogues in the field of supercapacitor electrodes in addition to potential future improvements.

Facile Fabrication of MnCo2O4/NiO Flower-Like Nanostructure Composites with Improved Energy Storage Capacity for High-Performance Supercapacitors

Over the past few decades, the application of new novel materials in energy storage system has seen excellent development. We report a novel MnCo₂O₄/NiO nanostructure prepared by a simplistic chemical bath deposition method and employed it as a binder free electrode in the supercapacitor. The synergistic attraction from a high density of active sites, better transportation of ion diffusion and super-most electrical transportation, which deliver boost electrochemical activities. X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy have been used to investigate the crystallinity, morphology, and elemental composition of the as-synthesized precursors, respectively. Cyclic voltammetry, galvanostatic charge/discharge, and electron impedance spectroscopy have been employed to investigate the electrochemical properties. The unique nanoparticle structures delivered additional well-organized pathways for the swift mobility of electrons and ions. The as-prepared binder-free MnCo₂O₄/NiO nanocomposite electrode has a high specific capacity of 453.3 C g⁻¹ at 1 Ag⁻¹, and an excellent cycling reliability of 91.89 percent even after 4000 cycles, which are significantly higher than bare MnCo₂O₄ and NiO electrodes. Finally, these results disclose that the as-fabricated MnCo₂O₄/NiO electrode could be a favored-like electrode material holds substantial potential and supreme option for efficient supercapacitor and their energy storage-related applications.

Metal sensing-carbon dots loaded TiO2-nanocomposite for photocatalytic bacterial deactivation and application in aquaculture

Nowadays, bioactive nanomaterials have been attracted the researcher's enthusiasm in various fields. Herein, Diplocyclos palmatus leaf extract-derived green-fluorescence carbon dots (DP-CDs) were prepared using the hydrothermal method. Due to the strong fluorescence stability, the prepared DP-CDs were coated on filter-paper to make a fluorometric sensor-strip for Fe3+ detection. After, a bandgap-narrowed DP-CDs/TiO2 nanocomposite (DCTN) was prepared using the methanolic extract of D. palmatus. The prepared DCTN exhibited improved photocatalytic bacterial deactivation under sunlight irradiation. The DCTN-photocatalysis slaughtered V. harveyi cells by the production of reactive oxygen species, which prompting oxidative stress, damaging the cell membrane and cellular constituents. These results suggest the plausible mode of bactericidal action of DCTN-photocatalysis under sunlight. Further, the DCTN has shown potent anti-biofilm activity against V. harveyi, and thereby, DCTN extended the survival of V. harveyi-infected shrimps during the in vivo trial with Litopenaeus vannamei. Notably, this is the first report for the disinfection of V. harveyi-mediated acute-hepatopancreatic necrosis disease (AHPND) using nanocomposite. The reduced internal-colonization of V. harveyi on the hepatopancreas as well as the rescue action of the pathognomonic effect in the experimental animals demonstrated the anti-infection potential of DCTN against V. harveyi-mediated AHPND in aquaculture.

Improved light-harvesting and suppressed charge recombination by introduction of a nanograss-like SnO2 interlayer for efficient CdS quantum dot sensitized solar cells

Quantum dot sensitized solar cell (QDSSC) performance is primarily limited by the recombination of charges at the interfaces of TiO₂/quantum dot (QD) sensitizer/electrolyte. Hence, blocking or suppressing the charge recombination is an essential requirement to elevate the QDSSC performance to the next level. To retard the charge recombination, herein, we propose the introduction of a SnO₂ nanograss (NG) interlayer on the surface of TiO₂ using the facile chemical bath deposition method. The SnO₂ NG interlayer not only inhibits the interfacial recombination processes in QDSSCs but also enhances the light-harvesting capability in generating more excitons. Hence, the TiO₂/SnO₂ NG/CdS QDSSCs can achieve the power conversion efficiency of 3.15%, which is superior to that of a TiO₂/CdS device (2.16%). Electrochemical impedance spectroscopy, open-circuit voltage decay and dark current analyses confirm that the recombination of charges at the photoanode/electrolyte interface is suppressed and the life time is improved by introducing the SnO₂ NG interlayer between the TiO₂ and CdS QD sensitizer.

Effect of the cobalt and zinc ratio on the preparation of zeolitic imidazole frameworks (ZIFs): synthesis, characterization and supercapacitor applications

The effect of the cobalt nitrate hexahydrate/zinc nitrate hexahydrate molar ratio on the physicochemical features of the zeolitic imidazole framework (ZIF) was studied.

NiMoO4@NiWO4 honeycombs as a high performance electrode material for supercapacitor applications

NiMoO₄@NiWO₄ electrode with honeycomb-like structure exhibits very good specific capacitance and cyclic stability than the NiMoO₄ electrode.

Facile synthesis of a NiO/NiS hybrid and its use as an efficient electrode material for supercapacitor applications

Cost-effective NiO/NiS nanosheets decorated with nanoparticles were successfully fabricated on Ni foam by carrying out a simple two-step hydrothermal synthesis. The resultant NiO/NiS composite electrode exhibited better specific capacitance and cyclic stability than did a NiO electrode.

Facile synthesis of hierarchical ZnMn2O4@ZnFe2O4 microspheres on nickel foam for high-performance supercapacitor applications

ZnMn₂O₄@ZnFe₂O₄ microsphere-like structures exhibit superior specific capacitance and cyclic stability than the ZnMn₂O₄ and ZnFe₂O₄ electrodes.

Facile preparation of nanoflake MnNi2O4–PbS nanoparticle composites on Ni foam as advanced electrode materials for supercapacitors

Nanoparticle decorated nanoflake-like structures of MnNi₂O₄–PbS composites exhibit superior supercapacitor performance to the MnNi₂O₄ electrode.

Hydrothermal synthesis of MoS2 and WS2 nanoparticles for high-performance supercapacitor applications

As-fabricated nanoparticle structured MoS₂ and WS₂ electrodes delivered high specific capacitance, excellent rate capability and good cycling stability.

Hierarchical nanostructured MnCo2O4–NiCo2O4 composites as innovative electrodes for supercapacitor applications

Hierarchical MnCo₂O₄–NiCo₂O₄ nanostructures deliver a higher electrochemical performance than MnCo₂O₄ and NiCo₂O₄ electrodes.

Carbon nanotube/metal-sulfide composite flexible electrodes for high-performance quantum dot-sensitized solar cells and supercapacitors

Carbon nanotubes (CNT) and metal sulfides have attracted considerable attention owing to their outstanding properties and multiple application areas, such as electrochemical energy conversion and energy storage. Here we describes a cost-effective and facile solution approach to the preparation of metal sulfides (PbS, CuS, CoS, and NiS) grown directly on CNTs, such as CNT/PbS, CNT/CuS, CNT/CoS, and CNT/NiS flexible electrodes for quantum dot-sensitized solar cells (QDSSCs) and supercapacitors (SCs). X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy confirmed that the CNT network was covered with high-purity metal sulfide compounds. QDSSCs equipped with the CNT/NiS counter electrode (CE) showed an impressive energy conversion efficiency (η) of 6.41% and remarkable stability. Interestingly, the assembled symmetric CNT/NiS-based polysulfide SC device exhibited a maximal energy density of 35.39 W h kg-1 and superior cycling durability with 98.39% retention after 1,000 cycles compared to the other CNT/metal-sulfides. The elevated performance of the composites was attributed mainly to the good conductivity, high surface area with mesoporous structures and stability of the CNTs and the high electrocatalytic activity of the metal sulfides. Overall, the designed composite CNT/metal-sulfide electrodes offer an important guideline for the development of next level energy conversion and energy storage devices.

Facile one-step synthesis of a composite CuO/Co3O4 electrode material on Ni foam for flexible supercapacitor applications

CuO/Co₃O₄ nanospheres were grown on Ni foam via a simple, one-step hydrothermal synthesis. The resultant CuO/Co₃O₄ composite electrode exhibits superior specific capacitance and cyclic stability compared to the Co₃O₄ electrode.