Cryo-Exfoliation Synthesis of Borophene and its Application in Wearable Electronics.

Borophene, an anisotropic Dirac Xene, exhibits diverse crystallographic phases, including metallic β₁₂, χ₃, and semiconducting α phases, alongside exceptional properties such as high electronic mobility, superior Young's modulus, thermal conductivity, superconductivity, and ferroelasticity. These attributes position borophene as a promising material for energy storage, electrocatalysis, and wearable electronics. However, its widespread application is hindered by existing synthesis methods that are expensive, complex, and yield-limited. This study presents a novel, cost-effective, environmentally friendly cryo-exfoliation method for borophene synthesis. Crystalline boron powder is rapidly quenched in liquid nitrogen and subjected to mild sonication, producing borophene with lateral dimensions of ≈50 to 10 µm and few-layer thicknesses. Advanced characterizations, including Atomic Force Microscopy (AFM), High-Resolution Transmission Electron Microscopy (HRTEM), Raman Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS), confirm structural integrity, chemical purity, and minimal surface oxidation. Molecular dynamics simulations further elucidate the weakened inter-layer coupling induced by cryo-processing. The integration of borophene into Polyvinylidene Fluoride (PVDF) nanocomposites demonstrates its potential for wearable electronics, achieving motion-sensitive devices with outstanding performance, generating output voltages up to ≈40 V. This scalable cryo-exfoliation approach paves the way for borophene-based applications in energy harvesting, sensing, and next-generation electronics.