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MXenes, a rapidly growing family of two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (Mn+1XnTx, where M is a transition metal, X is carbon, nitrogen, or both, and T represents surface functional groups), have captured the scientific community's interest due to their exceptional physicochemical properties and diverse technological applications. This comprehensive review explores the latest breakthroughs in MXene synthesis and characterisation, emphasising their multifaceted applications in energy storage, catalysis, sensing, and other cutting-edge domains. This review examines the most widely used MXene synthesis strategies, including selective etching and delamination, and highlight recent advancements in controlling surface terminations, composition, and morphology. The influence of these synthetic parameters on MXene properties is discussed in detail. Characterisation techniques, ranging from spectroscopic methods to electron microscopy, are essential for elucidating MXenes' structure-property relationships. Research into energy storage leverages MXenes' high electrical conductivity, large surface area, and chemical tunability. This has led to significant progress in the field. This paper presents research efforts focused on optimising MXenes for both battery and supercapacitor applications. Additionally, the catalytic prowess of MXenes, particularly in electrocatalysis and photocatalysis, is explored, emphasising their role in green energy technologies and environmental remediation. MXenes' remarkable sensitivity and selectivity make them promising candidates for sensing various gases, biomolecules, and ions, offering exciting possibilities in healthcare and environmental monitoring. Importantly, this review underscores the need for continued optimisation of MXene synthesis protocols to achieve large-scale production, enhanced stability, and precise control over properties across various fields.

Defects in nanomaterials have emerged as a pivotal aspect influencing their properties and diverse applications across numerous industries. This comprehensive review explores the intricate relationship between defects, primarily in carbon nanotubes and graphene, and their implications across a spectrum of applications. Beginning with an introduction delving into the significance and types of defects, the review elucidates their multifaceted impact on the mechanical, electrical, and environmental characteristics of these nanomaterials. It presents detailed analyses of studies exploring defects in carbon nanotubes and graphene, shedding light on their effects on mechanical and electrical properties, alongside characterizing methods. The paper meticulously examines the extensive array of applications involving carbon nanotubes and graphene, encompassing electronics, biomedical advancements, and considerations for environmental sustainability. Furthermore, it systematically incorporates studies highlighting the implications of defects on these applications. This review precisely examines defect engineering in nanomaterials across various industries, emphasizing the nuanced role of defects in tailoring properties for specific applications. It concludes by summarizing the integral role defects play in shaping the future of nanomaterial applications in diverse industries.

The study of electromagnetic (EM) wave absorbing materials is a natural response to ever-worsening EM wave pollution in modern days. Several nanomaterials have been explored as wideband, low-thickness, and lightweight microwave absorbing materials (MAMs) for use in both military and civilian realms but require significant improvement. This work presents the synthesis and charcaterization of in situ exfoliated boron nitride coated nickel ferrite (NiFBN) with excellent porous microstructure, using a simple auto-combustion method as well as the fabrication of a NiFBN-multiwalled carbon nanotube (MWCNT)-epoxy-based lightweight, thin nanocomposite for wideband microwave absorption (X-band). With a 2 mm thick sample, the 15-NiFBN-0.75_2mm nanocomposite exhibits effective absorption bandwidth (EAB) of 3.9 GHz and −59.38 dB reflection loss minima (RLmin). Several percentages of boron nitride with nickel ferrite were synthesized using the sol–gel auto-combustion process, and the MWCNT percentage was adjusted for enhanced microwave absorption.

This work explores the smart combination of functionalized boron nitride (mK-BN) and carbon nanotube (CNT), stabilized with copper oxide (CuO), as a highly stable, flexible supercapacitor electrode in low-cost viable ionic electrolyte. Oxy-surface modified boron nitride (BN) was introduced to induce supplementary acceptor and donor energy levels for charge transport. Incorporation of CNT facilitated the charge storage through EDLC mechanism and also reduced internal resistance. In three-electrode analysis, CuO/mK-BN/CNT nanohybrid exhibited specific capacitance (Csp) of 425 F/g in aqueous KCl. An asymmetric supercapacitor (ASC) device using CuO/mK-BN/CNT as cathode achieved a Cspof 80 F/g and 36 Wh/kg energy density with ⁓88 % stability after 25,000 charging-discharging cycles in organic electrolyte. To further boost the capacitive performance, energy density, and rate capability of the ASC device, a low-cost, solvent free, and viable ionic electrolyte [(NEt3H)+(HSO4)−] was introduced. In ionic electrolyte, device showed a maximum Cspof 132 F/g with an enhanced energy density of 59.4 W h/kg. ASC devices in ionic electrolyte also exhibited superior volumetric energy density of 1.410 mW h/cm3and excellent electrochemical performances after connecting two cells in parallel or in series combination implying the capability of the device to produce different required capacitance and potential for practical application. Finally, a flexible ASC device with the ionic electrolyte was also tested. This work established that with the smart combination of additional energy level induced functionalized BN, conducting nanotubes, and pseudocapacitive CuO, a highly stable, flexible asymmetric supercapacitor device can be fabricated with high energy density.

•Capable of storing and releasing large amounts of energy, phase change material (PCM) is a substance with a high heat of fusion which, melting and solidifying at a certain temperature.•The nanocarbons family e.g. CNTs, exfoliated graphite and graphene oxide (GO), owing to their superlative intrinsic mechanical and chemical properties which are very useful in various applications.•Various carbon based i.e. carbon Nanotubes, graphene etc. phase change materials including recent applications in Textiles, buildings, heat therapy packs,electronics, and packaging etc. are reviewed in this article.

Large-volume oscillations, poor stability, and low inherent conductivity of bare SnS2cause poor charge storage capacity, not expected for supercapacitor devices. In this study, we demonstrate an in situ growth of SnS2on functionalized boron nitride (mK-BN)/carbon nanotube (CNT) using a facile template-free hydrothermal method to introduce supplementary energy levels for electron transport, appropriate for an electrochemical device. Facile surface functionalization on BN provides the additional conducting energy levels for improved charge storage mechanism. Compounding of BN and SnS2improves the pseudocapacitive contribution of the electrode through a redox reaction as well as stability. Layered BN and CNT can alter the surface texture and surface area of the electrodes, which is important for the charge storage mechanism. X-ray photoelectron spectroscopy and X-ray diffraction analyses confirm the formation of composites, possible interactions among the individual components, and intercalation of layered materials. In the three-electrode electrochemical study, SnS2/mK-BN/CNT reveals a specific capacitance of 433 F/g in an aqueous electrolyte. An asymmetric supercapacitor device is fabricated using SnS2/mK-BN/CNT and 1 M TEABF4/dimethyl sulfoxide as the cathode and the electrolyte, respectively. The device exhibits the maximum specific capacitance of 87 F/g and an energy density of 49 W h/kg with 101% cyclic stability. Supplementary energy levels realized through the smart combination of SnS2, mK-BN, and CNT make SnS2/mK-BN/CNT perfect for a supercapacitor and will open avenues for next-generation applications of this SnS2-based composite material for advanced supercapacitors.

•Template-free synthesis of quaternary nanohybrid based on zinc cobalt sulphide, BN, CNT, polypyrrole.•Tuning behaviour of BN in electrochemical activity.•Capacitance retention of 106% after 10,000 cycles for quaternary nanohybrid.•Asymmetric supercapacitor device exhibited maximum specific energy of 49.6 Wh/kg.