Designing metal oxide-vertical graphene nanosheets structures for 2.6 V aqueous asymmetric electrochemical capacitor

Carbon-Based Nanomaterials Decorated Electrospun Nanofibers in Biosensors: A Review

Nanomaterials have revolutionized scientific research due to their exceptional physical and chemical capabilities. Carbon-based nanomaterials such as graphene and its derivates have excellent electrical, optical, thermal, physical, and chemical properties that have made them indispensable in several industries worldwide, including medicine, electronics, and energy. By incorporating carbon-based nanomaterials as nanofillers in electrospun nanofibers (ESNFs), smoother and highly conductive nanofibers can be achieved that possess a large surface area and porosity. This approach provides a superior alternative to traditional materials in the development of improved biosensors. Carbon-based ESNFs, among the most exciting new-generation materials, have many applications, including filtration, pharmaceuticals, biosensors, and membranes. The electrospinning technique is a highly efficient and cost-effective method for producing desired nanofibers compared to other methods. Various types of natural and synthetic organic polymers have been successfully utilized in solution electrospinning to produce nanofibers directly. To create diagnostics devices, various biomolecules like antibodies, enzymes, aptamers, ligands, and even cells can be bound to the surface of nanofibers. Electrospun nanofibers can serve as an immobilization matrix to create a biofunctional surface. Thus, biosensors with desired features can be produced in this way. This study comprehensively reviews biosensors that integrate nanodiamonds, fullerenes, carbon nanotubes, graphene oxide, and carbon dots into electrospun nanofibers.

A review of vertical graphene and its energy storage system applications

The pursuit of advanced materials to meet the escalating demands of energy storage system has led to the emergence of vertical graphene (VG) as a highly promising candidate. With its remarkable strength, stability, and conductivity, VG has gained significant attention for its potential to revolutionize energy storage technologies. This comprehensive review delves deeply into the synthesis methods, structural modifications, and multifaceted applications of VG in the context of lithium-ion batteries, silicon-based lithium batteries, lithium-sulfur batteries, sodium-ion batteries, potassium-ion batteries, aqueous zinc batteries, and supercapacitors. The review elucidates the intricate growth process of VG and underscores the paramount importance of optimizing process parameters to tailor VG for specific applications. Subsequently, the pivotal role of VG in enhancing the performance of various energy storage and conversion systems is exhaustively discussed. Moreover, it delves into structural improvement, performance tuning, and mechanism analysis of VG composite materials in diverse energy storage systems. In summary, this review provides a comprehensive look at VG synthesis, modification, and its wide range of applications in energy storage. It emphasizes the potential of VG in addressing critical challenges and advancing sustainable, high-performance energy storage devices, providing valuable guidance for the development of future technologies.

Mössbauer spectroscopic investigations on iron oxides and modified nanostructures: A review

Pure and doped iron oxide and hydroxide nanoparticles are highly potential materials for biological, environment, energy and other technological applications. On demand of the applications, single phase as well as multiple phase of different polymorphs or composites of iron oxides with compatible materials for example, zeolite, SiO₂, or Au are prepared. The properties of the as-synthesized nanoparticles are predominantly dictated by the local structure and the distribution of the cations. Mössbauer spectroscopy is a perfect and efficient characterization technique to investigate the local structure of the Mössbauer-active element such as Fe, Au, and Sn. In the present review, the local structure transformation on the optimization of the magnetite coexisted with iron hydroxides, spin dynamics of the bare, caped, core-shell and the composites of iron oxide nanoparticles (IONPs), dipole-dipole interactions and the diffusion of IONPs were discussed, based on the findings using Mössbauer spectroscopy.

The Enhanced Energy Density of rGO/TiO2 Based Nanocomposite as Electrode Material for Supercapacitor

TiO2 electrode material is a poor choice for supercapacitor electrodes because it has low conductivity, poor cyclic stability, and a low capacitance value. It is inevitable to enhance electrode materials of this kind by increasing the surface area and combining high electronic conductivity materials. In the current research work, it was proposed to combine reduced graphene oxide (rGO) as it might provide a large surface area for intercalation and deintercalation, and also, it could establish the shorter paths to ion transfer, leading to a reduction in ionic resistance. The size, surface morphology, and crystalline structure of as-prepared rGO/TiO2 nanocomposites were studied using HRTEM, FESEM, and XRD, respectively. Using an electrochemical workstation, the capacitive behaviors of the rGO/TiO2 electrode materials were assessed with respect to scan rate and current density. The capacitances obtained through cyclic voltammetry and galvanostatic charge-discharge techniques were found to be higher when compared to TiO2 alone. Furthermore, the as-synthesized nanocomposites were able to achieve a higher energy density and better cycle stability.

Review of Vertical Graphene and its Applications

Vertical graphene (VG) is a thin-film complex material featuring hierarchical microstructures: graphene-containing carbon nanosheets growing vertically on its deposition substrate, few-layer graphene basal layers, and chemically active atomistic defect sites and edges. Thanks to the fundamental characteristics of graphene materials, e.g. excellent electrical conductivity, thermal conductivity, chemical stability, and large specific surface area, VG materials have been successfully implemented into various niche applications which are strongly associated with their unique morphology. The microstructure of VG materials can be tuned by modifying growth methods and the parameters of growth processes. Multiple growth processes have been developed to address faster, safer, and mass production methods of VG materials, as well as accommodating various applications. VG's successful applications include field emission, supercapacitors, fuel cells, batteries, gas sensors, biochemical sensors, electrochemical analysis, strain sensors, wearable electronics, photo trapping, terahertz emission, etc. Research topics on VG have been more diversified in recent years, indicating extensive attention from the research community and great commercial value. In this review article, VG's morphology is briefly reviewed, and then various growth processes are discussed from the perspective of plasma science. After that, the most recent progress in its applications and related sciences and technologies are discussed.

Alkali-cation-incorporated and functionalized iron oxide nanoparticles for methyl blue removal/decomposition

Enhancing the rate of decomposition or removal of organic dye by designing novel nanostructures is a subject of intensive research aimed at improving waste-water treatment in the textile and pharmaceutical industries. Despite radical progress in this challenging area using iron-based nanostructures, enhancing stability and dye adsorption performance is highly desirable. In the present manuscript alkali cations are incorporated into iron oxide nanoparticles (IONPs) to tailor their structural and magnetic properties and to magnify methyl blue (MB) removal/decomposition capability. The process automatically functionalizes the IONPs without any additional steps. The plausible mechanisms proposed for IONPs incubated in alkali chloride and hydroxide solutions are based on structural investigation and correlated with the removal/adsorption capabilities. The MB adsorption kinetics of the incubated IONPs is elucidated by the pseudo second-order reaction model. Not only are the functional groups of -OH and -Cl attached to the surface of the NPs, the present investigation also reveals that the presence of alkali cations significantly influences the MB adsorption kinetics and correlates with the cation content and atomic polarizability.

Recent Advances on Boosting the Cell Voltage of Aqueous Supercapacitors

Due to its ultra-fast charge/discharge rate, long cyclic life span, and environmental benignity, aqueous supercapacitor (SC) is considered as a proper next-generation energy storage device. Unfortunately, limited by undesirable water electrolysis and unreasonable electrode potential range, aqueous SC normally generates a narrow cell voltage, resulting in a low energy density. To address such challenge, enormous efforts have been made to construct high-voltage aqueous SCs. Despite these achievements, the systematic reviews about this field are still rare. To fill this knowledge gap, this review summarizes the recent advances about boosting the cell voltage of aqueous SCs. From the viewpoint of electrode, doping alkali cations, modulating the electrode mass ratio, and optimizing the surface charge density are regarded as three effective pathways to achieve this goal. However, adjusting the appropriate pH level, introducing redox mediators, and constructing "water-in-salt" electrolyte are other three universal routes from the electrolyte aspect. Furthermore, it is also effective to obtain the high-voltage aqueous SCs through asymmetric design, such as designing asymmetric SCs. The confronting challenges and future development tendency towards the high-voltage aqueous SCs are further discussed.

Electrochemical Assessment of As-Deposited Co(OH)2 by Electrochemical Synthesis: The Effect of Synthesis Temperature on Performance

In this paper, the influence of an electrolytic temperature bath was used in the electrodeposition process on the size, color, and shape of the as-deposited Co(OH)2, and the electrochemical performance was investigated. Three different temperatures of 25, 60, and 95 °C were evaluated for the electrodeposition of Co(OH)2 on stainless steel plates (SSP). The electrochemical performance of the as-deposited electrodes (SSP) was measured in a symmetric electrochemical cell (EC) arrangement. XRD, SEM, and N2 physisorption analyses were carried out to evaluate the structure and morphological composition, along with the textural properties. Results showed that the hexagonal platelet micro-clusters of Co(OH)2 are formed in a mixed composition of both α-Co(OH)2 and β-Co(OH)2 phases, with the α-Co(OH)2 phase being the major phase formed in the electrodeposition process at temperatures below 95 °C, as suggested by the XRD analysis. Electrochemical cell performances were evaluated by galvanostatic cycling, results showed maximum areal capacity values of 1.97, 2.69, and 4.34 mA h cm–2 at a charge/discharge current of 6.25mA cm–2, for the as-deposited materials at 25, 60 and 95 °C, respectively. The specific power of the EC reached up to 19 kW kg–1 for the EC obtained material at 60 °C, with a specific energy of 2.8 W h kg–1. The maximum specific energy was reached at a current density of 6.25 mA cm−2, with a value of 10.79 W h kg–1 for the EC at 60 °C. These results offer some insight into how the morphology and composition of thin films can be tuned by the electrochemical synthesis temperature, yielding different electrochemical performances and areal capacity behaviors.

A Rapid Synthesis of Mesoporous Mn2O3 Nanoparticles for Supercapacitor Applications

Mn2O3 nanomaterials have been recently composing a variety of electrochemical systems like fuel cells, supercapacitors, etc., due to their high specific capacitance, low cost, abundance and environmentally benign nature. In this work, mesoporous Mn2O3 nanoparticles (NPs) were synthesized by manganese acetate, citric acid and sodium hydroxide through a hydrothermal process at 150 °C for 3 h. The synthesized mesoporous Mn2O3 NPs were thoroughly characterized in terms of their morphology, surfaces, as well as their crystalline, electrochemical and electrochemical properties. For supercapacitor applications, the synthesized mesoporous Mn2O3 NP-based electrode accomplished an excellent specific capacitance (Csp) of 460 F·g−1 at 10 mV·s−1 with a good electrocatalytic activity by observing good electrochemical properties in a 6 M KOH electrolyte. The excellent Csp might be explained by the improvement of the surface area, porous surface and uniformity, which might favor the generation of large active sites and a fast ionic transport over the good electrocatalytic surface of the Mn2O3 electrode. The fabricated supercapacitors exhibited a good cycling stability after 5000 cycles by maintaining ~83% of Csp.

Graphene Oxide and Its Inorganic Composites: Fabrication and Electrorheological Response

Composite particles associated with graphene oxide (GO) and inorganic materials provide the synergistic properties of an appropriate electrical conductivity of GO with the good dielectric characteristics of inorganic materials, making them attractive candidates for electrorheological (ER) materials. This review paper focuses on the fabrication mechanisms of GO/inorganic composites and their ER response when suspended in a non-conducting medium, including steady shear flow curves, dynamic yield stress, On-Off tests, and dynamic oscillation analysis. Furthermore, the morphologies of these composites, dielectric properties, and sedimentation of the ER fluids are covered.