The advent of two-dimensional (2D) materials and their capacity to form van der Waals (vdW) heterostructures has revolutionized numerous scientific fields, including electronics, optoelectronics, and energy storage. This paper presents a comprehensive investigation of bandgap engineering and band structure prediction in 2D vdW heterostructures utilizing density functional theory (DFT). By combining various 2D materials, such as graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides, and blue phosphorus, these heterostructures exhibit tailored properties that surpass those of individual components. Bandgap engineering represents an effective approach to addressing the limitations inherent in material properties, thereby providing enhanced functionalities for a range of applications, including transistors, photodetectors, and solar cells. Furthermore, this study discusses the current limitations and challenges associated with bandgap engineering in 2D heterostructures and highlights future prospects aimed at unlocking their full potential for advanced technological applications.

Zinc-ion batteries (ZIBs) are regarded as one of the promising next-generation energy storage technologies due to their high volumetric capacity, cost-effectiveness, and high safety. MXene materials, featuring a unique two-dimensional (2D) layered structure, excellent conductivity, and tunable surface chemistry, have been widely applied in energy storage systems. This review summarizes the recent progress in experimental and computational strategies for MXene-based ZIBs. The construction of MXene-based electrodes and the effect mechanisms of Zn-ion transport facilitation, electrode cycling stability, and anode dendrite suppression are discussed. Subsequently, the theoretical simulation strategies for MXene performance investigation are analyzed, including surface chemistry and defect engineering of MXene-based electrodes and the rational design of heterostructure interfaces for enhancing conductivity and suppressing Zn dendrite growth. Finally, the review outlines the major challenges that currently hinder the applications of MXene in ZIBs and proposes future research directions, offering insights that may guide the continued advancement of next-generation MXene-based energy storage systems.

Graphene quantum dots (GQDs) with a band gap have been widely applied in many fields owing to their unique optical properties. To better utilize the optical advantages of GQDs, it is important to understand their optical characteristics. Our study demonstrates the optical properties and carrier behaviors of synthesized graphene oxide quantum dot (GOQD) and reduced graphene oxide quantum dot (rGOQD) pellets via Terahertz time-domain spectroscopy (THz-TDS). The complex permittivity and optical conductivity are obtained in the terahertz region, indicating that the optical conductivity of the GOQD is higher than that of the rGOQD. Although rGOQD has a higher carrier density, approximately 1.5-times than that of GOQD, the lower charge carrier mobility of the rGOQD, which is obtained using Drude–Lorentz oscillator model fitting contributes to a decrease in optical conductivity. This lower mobility can be attributed to the more significant number of defect states within the rGOQD compared to GOQD. To the best of our knowledge, our study initially demonstrates the optical property and carrier behaviors of GOQD and rGOQD in the THz region. Moreover, this study provides important information on factors influencing carrier behavior to various fields in which carrier behavior plays an important role.

Lithium-ion capacitors (LICs) are next-generation electrochemical storage devices that combine the benefits of both supercapacitors and lithium-ion batteries. Silicon materials have attracted attention for the development of high-performance LICs owing to their high theoretical capacity and low delithiation potential (∼0.5 V versus Li/Li⁺). However, sluggish ion diffusion has severely restricted the development of LICs. Herein, a binder-free anode of boron-doped silicon nanowires (B-doped SiNWs) on a copper substrate was reported as an anode for LICs. B-doping could significantly improve the conductivity of the SiNW anode, which could enhance electron/ion transfer in LICs. As expected, the B-doped SiNWs//Li half-cell delivered a higher initial discharge capacity of 454 mAh g⁻¹ with excellent cycle stability (capacity retention of 96% after 100 cycles). Furthermore, the near-lithium reaction plateau of Si endows the LICs with a high voltage window (1.5–4.2 V), and the as-fabricated B-doped SiNWs//AC LIC possesses the maximum energy density value of 155.8 Wh kg⁻¹ at a battery-inaccessible power density of 275 W kg⁻¹. This study provides a new strategy for using Si-based composites to develop high-performance LIC.