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Due to its superior advantages in terms of electronegativity, metallic conductivity, mechanical flexibility, customizable surface chemistry, etc., 2D MXenes for nanogenerators have demonstrated significant progress. In order to push scientific design strategies for the practical application of nanogenerators from the viewpoints of the basic aspect and recent advancements, this systematic review covers the most recent developments of MXenes for nanogenerators in its first section. In the second section, the importance of renewable energy and an introduction to nanogenerators, major classifications, and their working principles are discussed. At the end of this section, various materials used for energy harvesting and frequent combos of MXene with other active materials are described in detail together with the essential framework of nanogenerators. In the third, fourth, and fifth sections, the materials used for nanogenerators, MXene synthesis along with its properties, and MXene nanocomposites with polymeric materials are discussed in detail with the recent progress and challenges for their use in nanogenerator applications. In the sixth section, a thorough discussion of the design strategies and internal improvement mechanisms of MXenes and the composite materials for nanogenerators with 3D printing technologies are presented. Finally, we summarize the key points discussed throughout this review and discuss some thoughts on potential approaches for nanocomposite materials based on MXenes that could be used in nanogenerators for better performance.

Supercapacitors (SCs) have fascinating potential for the energy storage systems of the future due to their exceptional power delivery and quick charge and discharge capabilities. However, its energy density continues to be a barrier to its general use. This study investigates the electrochemical properties of electrospun polyacrylonitrile (PAN) nanofiber (NF) composites embedded with cobalt hydroxide (Co(OH)2) nanoparticles (NPs) for SC electrodes. The synthesis of CNFs involves electrospinning PAN solutions loaded with Co(OH)2 precursors, followed by heat treatment to enhance structural integrity and electrochemical performance. The crystallographic and morphological study of the composite fibres was conducted through different characterization methods. The electrochemical performance of Co3O4/PAN CNFs-based composite electrodes is evaluated through CV, GCD, and EIS measurements, revealing their suitability for SC applications. The findings reveal that the synergistic effects of Co3O4 NPs within the PAN NFs contribute to enhanced specific capacitance, cyclic stability, and rate capability, thus offering significant prospects for the development of high-performance SCs. The Co3O4/PAN CNFs//AC device is constructed using PVA/KOH gel electrolyte, which demonstrated an energy density of 11.19 Whkg−1 at a power density of 1000 Wkg−1. The device exhibits 69% capacitance retention over 3000 cycles at 100 mVs−1, indicating strong cycling stability and electrochemical reversibility, which are crucial for practical applications. [ABSTRACT FROM AUTHOR]

The photothermal energy conversion mechanism in pseudocapacitive nanoelectrodes endures temperature-enervated power dissipation due to self-heating, leading to rapid heating and cooling cycles during the redox reactions triggered by plasmonic excitation. Herein, we report on vanadium nitride (VN)-intercalated reduced graphene oxide (RGO) nanosheets (VN@RGO) as a photoresponsive pseudocapacitive electrode material. Finite-difference time-domain (FDTD) simulations were used to analyze the photothermal-driven localized self-heating considering the complex dielectric properties of VN@RGO. The effect of morphology and stoichiometry on the polarization-induced electric field intensity (|E|2), power absorption (Pabs), and current density (J) of the VN@RGO system has been systematically explored. Both the simulation and experimental results complement each other. This study delineates electrically coupled thermal attenuation in VN@RGO, overcoming the limitations related to potential modulation of the electrode material. VN@RGO exhibits excellent electrochemical performance in the half-cell and full-cell modes of a symmetric supercapacitor, achieving maximum specific capacitances of 276 and 56 F g–1 at a current density of 0.1 A g–1, respectively. [ABSTRACT FROM AUTHOR]

MXene has been identified as a new emerging material for various applications including energy storage, electronics, and bio-related due to its wider physicochemical characteristics. Further the formation of hybrid composites of MXene with other materials makes them interesting to utilize in multifunctional applications. The selection of magnetic nanomaterials for the formation of nanocomposite with MXene would be interesting for the utilization of magnetic characteristics along with MXene. However, the selection of the magnetic nanomaterials is important, as the magnetic characteristics of the ferrites vary with the stoichiometric composition of metal ions, particle shape and size. The selection of the electrolyte is also important for electrochemical energy storage applications, as the electrolyte could influence the electrochemical performance. Further, the external magnetic field also could influence the electrochemical performance. This review briefly discusses the synthesis method of MXene, and ferrite magnetic nanoparticles and their composite formation. We also discussed the recent progress made on the MXene/ferrite nanocomposite for potential applications in electrochemical supercapacitor applications. The possibility of magnetic field-assisted supercapacitor applications with electrolyte and electrode materials are discussed.

Tin oxide (SnO2) and nitrogen-doped graphene quantum dots (N-GQDs) composite nanotubes (SnO2/N-GQD NTs) were fabricated by the electrospinning technique and followed by the thermal annealing method for the application in supercapacitor as an electrode. SnO2/N-GQD NTs with different ratio of N-GQDs were prepared by adding different ratios of N-GQDs along with tin chloride during the electrospinning process. The prepared composite's structure and morphological properties were characterized by using different techniques like XRD, FE-SEM, TEM, and XPS. The supercapacitor performance of the SnO2/N-GQD NTs composite was analyzed by the electrochemical studies such as cyclic voltammetry and galvanostatic charge-discharge (GCD) measurement in 2 M KOH solution as electrolyte. The electrochemical analyses of SnO2/N-GQD NTs was tested at different scan rates and current densities. SnO2/N-GQD NTs prepared using 3 wt.% of N-GQDs showed an excellent capacity retention even after 5000 GCD cycles and exhibited a maximum specific capacitance of 420 mF g-1 at a current density of 8 mA cm-2 in comparison to pure SnO2 NTs (230 mF cm-2). [ABSTRACT FROM AUTHOR]

Graphene oxide can be used to store energy, as electrodes and purify industrial and domestic wastewater as photocatalysts and adsorbents because of its remarkable thermal, electrical, and chemical capabilities. Toward understanding graphene oxide (GO) based nanomaterials considering the background factors, the present review study investigated their characteristics, preparation methods, and characterization processes. The removal of contaminants from wastewater has recently been a focus of attention for materials based on GO. Progress in GO synthesis and surface modification has shown that they can be used to immobilize enzymes. It is possible to immobilize enzymes with varying characteristics on graphene-oxide-based substrates without sacrificing their functioning, thus developing a new environmental remediation platform utilizing nano biocatalysts. GO doping and co-doping with a variety of heterogeneous semiconductor-based metal oxides were included in a brief strategy for boosting GO efficiency. A high band-gap material was also explored as a possibility for immobilization, which shifts the absorption threshold to the visible range and increases photoactivity. For water treatment applications, graphene-based nanomaterials were used in Fenton reactions, photocatalysis, ozonation, photo electrocatalysis, photo-Fenton, and a combination of photon-Fenton and photocatalysis. Nanoparticles made from GO improved the efficiency of composite materials when used for their intended applications. As a result of the analysis, prospects and improvements are clear, especially when it comes to scaling up GO-based wastewater treatment technologies. [Display omitted] • Nano-based graphene oxide (GO) is useful in effective wastewater treatment. • To develop GO to treat wastewater, bottom-up and top-down approaches can be used. • Electro-chemical, mechanical, and surface properties of GO are pollutant traps. • GO plays an important role in adsorption-based water treatment systems. [ABSTRACT FROM AUTHOR]