Bin Quan

MXenes, as an emerging 2D material, hold considerable energy storage potential. However, the intrinsic stochastic distribution and thermodynamic metastability of their surface functional groups impair key electrochemical properties, compromising their cyclability and rate capability. Regulating the type, density, and spatial arrangement of MXene surface functional groups is thus a pivotal strategy for optimizing the electrochemical performance. This review first focuses on the surface functional group modification mechanisms of MXenes leveraging ultrahigh conductivity, tunable interlayer spacing, and mechanical flexibility, including chemical etching thermodynamics and post‐synthetic modification chemistry. We then compare the distinct electrochemical effects of oxygen‐containing, halogen‐, and nitrogen/sulfur‐based functional groups on the ionic adsorption energetics, pseudocapacitive charge storage, and catalytic turnover frequency of MXenes. Subsequently, we detail the typical applications of MXenes surface functional group engineering in energy storage, extending from lithium‐sulfur batteries and supercapacitors to emerging frontiers including catalysis, sensing, water desalination, and biomedicine. This review attempts to establish a basic theoretical framework for optimizing MXene‐based energy storage materials, offering modest references for developing next‐generation high‐efficiency energy storage devices.

Uncovering the structural‐functional relationship between entropy‐driven phase structures and lattice distortion/points defect‐induced dielectric polarization has always been a long‐standing challenge in electromagnetic (EM) wave absorption field. In this work, a strategy of entropy‐driven phase engineering was proposed to regulate the evolution of EM spectra of carbon confined alloy composites. With increasing alloy entropy, the phase structure evolves from a single FCC phase to an FCC+BCC dual‐phase structure, accompanied by lattice distortion and point defects. These entropy‐induced effects effectively enhance electron scattering, moderately suppress excessive electrical conductivity, and weaken the skin effect, thereby significantly improving impedance matching. Moreover, abundant dual‐phase interfaces and lattice defects generate strong interfacial polarization and dipole polarization, which further boost dielectric loss. Importantly, polarization‐dominant medium‐entropy FeCoNiCu@C has been obtained by balancing the contribution between dielectric loss and impedance matching, as well as polarization loss and conduction loss, which realizes a broad effective absorption bandwidth (EAB) of 5.8 GHz at 1.8 mm and a minimum reflection loss ( RL ) of −42.19 dB at 3.85 mm. This work demonstrates that entropy‐driven phase engineering accompanied by lattice distortion and point defects provides an effective strategy to synergistically regulate the evolution of EM spectra, thus achieving high‐efficiency EM wave absorption performance.

Camouflage images corresponding to the four colors in an actual environment.

Z-shaped 3D metamaterials exhibit outstanding performances (RL _min of −20.75 dB with EAB of 12 GHz at 6.5 mm) due to the synergistic loss combining microscopic material loss and macroscopic structural consumption.

Iron‐based sulfides are promising candidates as anode in potassium‐ion rechargeable batteries due to their high specific capacity, the abundant and low‐cost iron sources, and environmental friendliness. However, issues like volume expansion, poor redox reversibility, and poor ion conductivity severely hinder the electrochemical performance during charging and discharging processes. To address these challenges, this work induced transition metals nickel and cobalt to construct a bimetallic co‐enhanced anode of iron‐based sulfide. Different schemes of calcination processes were designed, enabling the fabrication of all six types of composites of different calcination temperatures. Electrochemical tests reveal that the bimetallic synergy notably improves the redox reaction kinetics through structural regulation. Binary transition metal synergy facilitates potassium salt di‐intercalation, reduces interfacial resistance, and improves ionic conductivity. It was found that the introduction of element cobalt and the calcination process notably enhanced the stability of the anode materials, while the incorporation of nickel greatly improved their specific capacity. Notably, the cobalt‐introduced anode exhibited favorable potassium storage performance, retaining high specific capacity after cycling, indicating potential for practical application. This study highlights a versatile strategy for advancing stable, high‐performance iron‐based sulfide anodes of potassium‐ion rechargeable batteries.

Element doping can endow MXenes with enhanced electrochemical properties, catalytic performance, and structural characteristics. This review focuses on the doping mechanism, doping methods and applications of MXenes in the field of energy storage.

The lithium metal anode offers a high theoretical capacity (3860 mAh g^-1) and a low electrochemical potential (-3.040 V vs SHE). These properties make it a promising candidate for use as an anode in next-generation lithium-ion batteries. However, the uneven deposition and stripping of lithium lead to dendrite growth and instability of the solid electrolyte interface. These problems seriously hinder the practical application of lithium metal batteries. Stable Li anodes enabled by a uniform lithiophilic nucleation layer and photoassisted current collectors are highly desirable. However, only a few studies have explored this approach. In this work, a thin ZnO layer was conformally deposited onto a 3D current collector via atomic layer deposition (ALD) to achieve uniform and stable lithium metal growth. The ZnO layer serves as a lithium nucleation layer and provides photoresponsiveness, thereby facilitating subsequent photoassisted deposition. This modification induced local carrier redistribution, reduced the overpotential by 25.5 mV, and significantly enhanced the lithium deposition kinetics. A high Coulombic efficiency of 96.56% was achieved at 3 mA cm^-2 after 300 cycles. These findings provide valuable insights into the development of next-generation photoassisted Li metal anodes, highlighting their potential for improved performance and stability.