Liquid Metal-Assisted Large-Scale Exfoliation of Boron Nanosheet for High-Performance CO₂ Electroreduction

2D materials are increasingly recognized as promising candidates for next-generation catalysis, energy storage devices, and sustainable chemical transformations. Among 2D materials, boron nanosheets have attracted considerable attention due to their unique electronic structure and high surface reactivity. However, the synthesis of boron nanosheets remains exceptionally challenging. Here, we demonstrated a novel, scalable, surfactant-free, and simple room-temperature liquid metal-assisted mechanical exfoliation strategy that enables the AlB₂ transformation into few-layer boron nanosheets (BS). In this process, the liquid metal (LM) intercalates and disrupts the ionic interlayer forces. Its fluidic nature facilitates to readily form alloy with Al metal through energetically favorable and fast interfacial diffusion. While shear forces induced by ball milling drive the exfoliation of ultrathin BS at a large-scale yield (87.9%). The exfoliated BS possesses a large lateral size, with a thickness 1.96 ± 0.57 nm. The synergistic effect of exfoliated BS with silver nanoparticles exhibited remarkably enhanced CO₂ reduction performance, achieving superior activity, stability (>205 h), and selectivity (97.4%) toward CO production. This novel scalable exfoliation technique paves the new approach toward the large-scale synthesis of 2D materials and their potential use in catalytic applications.