Zhiyuan Shi

Two‐dimensional (2D) hexagonal boron nitride nanosheets (h‐BNNSs) are versatile platforms for thermal, mechanical, and catalytic applications. However, scalable preparation that preserves both structural integrity and economic feasibility is still a major bottleneck. Herein, we review the progress in the versatility of salt‐assisted preparation and modification of h‐BNNS, where ionic compounds enable a controllable physicochemical environment for material engineering. In bottom‐up synthesis, the molten salt medium enhances mass transfer and lowers reaction barriers, promoting controlled crystal growth. In top‐down exfoliation, ion intercalation overcomes the interlayer van der Waals force to enable efficient production of high‐quality nanosheets. Meanwhile, the chemically active ionic environment bridges preparation and modification, allowing elemental doping, interface engineering, and nanoparticle loading to tailor properties and expand applications. Finally, we summarize key bottlenecks and outline future directions toward scalable, controllable, and application‐oriented salt‐assisted h‐BNNS engineering.

Owing to its superior electrical and thermal conductivity and low cost, copper (Cu) is essential in power, communications, and electronics. However, ongoing device miniaturization poses critical challenges to its ampacity and environmental stability. In this study, vertical graphene-skinned Cu wires of 18 μm, 500 μm, and 1 mm in diameter were prepared using a solid carbon source without additional heating. The distinct graphene morphologies on Cu wires of different diameters stemmed from their dissimilar thermal responses and the effect of exposed catalytic area on growth. The growth process and structural characteristics of vertical graphene on 18 μm Cu wires were then investigated. Compared to horizontal graphene, vertical graphene offers superior oxidation resistance. While preserving the electrical performance of the Cu wires, vertical graphene enhances their thermal stability and current-carrying capacity. This work provides a coating strategy that integrates conductivity, heat dissipation, and durability for micro-wire protection in harsh environments.

球形铜粉在增材制造、柔性电子、电接触材料等领域的广泛应用要求其具有高球形度、高流动性和高抗氧化性. 典型球化工艺面临铜液滴粘连, 导致球形度不高、卫星粉、粉体粒径分布宽等问题. 此外, 先球化后包覆工艺路径复杂且制备周期长. 在粉体球化的同时引入功能包覆层不仅可以降低粉体粘连, 而且可以同步实现球形铜粉功能化. 石墨烯与铜的界面润湿性差, 其作为“蒙皮”可避免粉体粘连, 而且其高电子迁移率、抗水氧渗透特性可赋予其高电导、抗氧化等卓越性能. 本文提出高温重熔化学气相沉积技术, 铜粉和甲烷在高温立式炉中相向流动, 同步实现高球形度铜粉制取及铜表面高质量石墨烯薄膜包覆. 该方案耦合粉体球化(铜熔化并在表面张力作用下球化)过程和石墨烯生长(铜液滴表面甲烷裂解实现碳形核生长)过程. 最终, 在1400°C下获得球形度达0.89±0.11的高球形化铜粉体. 石墨烯(层数在10层以内)层间的有序排列结构表明其具有较高的结晶质量. 与裸铜粉相比, 蒙烯铜粉在经过NaOH腐蚀处理或空气氧化处理后, 展现出更好的抗氧化性能. 本文提出的高温重熔化学气相沉积技术可连续制备具有高球形度、高氧化温度的蒙烯铜粉, 有望成为规模化制备高性能球形铜粉的通用技术, 为其广泛应用提供材料基础.

High-quality two-dimensional hexagonal boron nitride (h-BN) film with tens of layers has been used as a universal substrate and capping layer for the van der Waals devices. Various approaches have been carried out for the synthesis of multilayered h-BN. Among them, the metal flux method is reliable in yielding h-BN crystals with high crystalline quality. However, this time- and energy-demanding method hinders its scale application. Herein, inspired by the metal flux method, we reported the time-effective growth of high-quality multilayered h-BN film (ca. 20 nm) on a molten Ni–B layer wetting on W substrate with chemical vapor deposition method. The film exhibits an excellent stacking sequence and a full-width at half maximum of the Raman E_2g peak narrow to 9.5 cm⁻¹. Cross-sectional high-resolution transmission electron microscopy and in-situ x-ray diffraction spectroscopy were carried out to investigate the crystal structure evolution of Ni–B layer wetting on W substrate. It is found that the low surface tension caused by the spreading of Ni–B alloy on the W substrate and the presence of the Ni subsurface may be responsible for the formation of multilayered h-BN with excellent crystalline quality. Meanwhile, the W diffusion in Ni–B-based melt can hinder the formation of h-BN under certain growth conditions. The approach demonstrates the feasibility of large-scale growth of multilayered h-BN, paving the way to future applications in van der Waals electronic and optoelectronic devices.