MXenes refer to a family of 2D transition metal carbides/nitrides that are rich in chemistry. The first member of the family, Ti₃C₂T_x, was reported in 2011. Since then MXenes have opened up an exciting new field in 2D inorganic functional materials by virtue of their intrinsic electronic conductivity, superior hydrophilicity, rich surface chemistry and layered structure, as evidenced by the fact that the number of papers on MXenes has increased exponentially. The unique properties and ease of processing have positioned them as promising materials for a variety of applications including energy storage, especially for supercapacitors. In this review, we aim to summarize the current advances in MXene research on supercapacitors. We begin by reviewing various fabrication routes and their influence on the structure and surface chemistry of MXenes. The structure, properties, stability, and species of layered MXenes are then introduced. The focus then turns to the capacitive energy-storage mechanisms and the factors determining the electrochemical behavior and performance in supercapacitors. Besides, various types of MXene-based supercapacitors are summarized to highlight the significance of MXenes in constructing energy storage devices. Finally, challenges and prospects in this booming field are proposed to promote further development of MXenes in supercapacitors.

Traditional ceramic materials are generally brittle and not flexible with high production costs, which seriously hinders their practical applications. Multifunctional nanofiber ceramic aerogels are highly desirable for applications in extreme environments, however, the integration of multiple functions in their preparation is extremely challenging. To tackle these challenges, we fabricated a multifunctional SiC@SiO₂ nanofiber aerogel (SiC@SiO₂ NFA) with a three-dimensional (3D) porous cross-linked structure through a simple chemical vapor deposition method and subsequent heat-treatment process. The as-prepared SiC@SiO₂ NFA exhibits an ultralow density (~ 11 mg cm^− 3), ultra-elastic, fatigue-resistant and refractory performance, high temperature thermal stability, thermal insulation properties, and significant strain-dependent piezoresistive sensing behavior. Furthermore, the SiC@SiO₂ NFA shows a superior electromagnetic wave absorption performance with a minimum refection loss (RL_min) value of − 50.36 dB and a maximum effective absorption bandwidth (EAB_max) of 8.6 GHz. The successful preparation of this multifunctional aerogel material provides a promising prospect for the design and fabrication of the cutting-edge ceramic materials.

Carbon spheres appeared for the first time during the process of etching Ti ₃ AlC ₂ using hydrofluoric acid.

Two-dimensional (2D) transition metal carbides (MXene) process attractive conductivity and abundant surface functional groups, providing immense potential in the field of electromagnetic wave (EMW) absorption. However, the high conductivity and spontaneous aggregation of MXene suffer from limited EMW response. Inspired by the dielectric-magnetic synergy effect, the strategy of decorating MXene with magnetic elements is expected to solve this challenge. In this work, zigzag-like Mo₂TiC₂ MXene nanofiber (Mo-MXene NFs) cross-linked networks are fabricated using HF etching and KOH shearing processes. Subsequently, Co-MOF and derived CoNi LDH ultrathin nanosheets are grown inside Mo-MXene NFs, and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo-MXene NFs network. Benefiting from the synergistic effect of highly dispersed small CoNi alloy nanoparticles, a 3D conductive network assembled by zigzag-like Mo-MXene NFs, numerous N-doped hollow carbon vesicles, and abundant dual heterogeneous interface, the designed Mo-MXene/CoNi-NC heterostructure provides robust EMW absorption ability with a reflection loss (R_L) value of -68.45 dB at a matching thickness of 4.38 mm. The robust EMW absorption performance can be attributed to the excellent dielectric losses, magnetic loss, impedance matching, and multiple scattering and reflection triggered by the unique 3D network structure. This work puts up great potential in developing advanced MXene-based EMW absorption devices.

Material composition and structural design are important factors influencing the electromagnetic wave (EMW) absorption performance of materials. To alleviate the impedance mismatch attributed to the high dielectric constant of Ti₃C₂T_x MXene, we have successfully synthesized core‐shell structured SiO₂@MXene@MoS₂ nanospheres. This architecture, comprising SiO₂ as the core, MXene as the intermediate layer, and MoS₂ as the outer shell, is achieved through an electrostatic self‐assembly method combined with a hydrothermal process. This complex core‐shell structure not only provides a variety of loss mechanisms that effectively dissipate electromagnetic energy but also prevents self‐aggregation of MXene and MoS₂ nanosheets. Notably, the synergistic combination of SiO₂ and MoS₂ with highly conductive MXene enables the suitable dielectric constant of the composites, ensuring optimal impedance matching. Therefore, the core‐shell structured SiO₂@MXene@MoS₂ nanospheres exhibit excellent EMW absorption performance, featuring a remarkable minimum reflection loss (RL_min) of −52.11 dB (2.4 mm). It is noteworthy that these nanospheres achieve an ultra‐wide effective absorption bandwidth (EAB) of 6.72 GHz. This work provides a novel approach for designing and synthesizing high‐performance EMW absorbers characterized by “wide bandwidth and strong reflection loss.”