Borophene: Crucial Challenges and the Way Forward.

Borophene, a monolayer of boron atoms, exhibits anisotropy in crystallographic structure and hence anisotropic physical and chemical behavior. It has emerged as a disruptive two-dimensional (2D) quantum material due to its exceptional electronic mobility, Young's moduli with half-auxetic nature of crystals and due to its chemical reactivity. Borophene exhibits polymorphism with structure dependent electronic nature. While metallic β & X phases and semiconducting α phase have already been explored, several new crystallographic phases are presently being explored. However, its cumbersome synthesis protocols remain a major challenge, hindering large-scale production of defect free borophene. Despite its advantages, borophene faces limitations such as oxidation sensitivity, phase instability, and the absence of a band gap. Strategies like defect engineering, surface functionalization, and 2D-2D hybridization offer potential solutions for band gap tuning and carrier injection. Device integration issues include imperfect interfaces, work function mismatch, interfacial charging etc. If these challenges can be overcome, borophene can then find applications in spintronics, photonics, flexible batteries, and quantum computing, paving the way for commercialization. This review highlights the current state-of-the-art of borophene research and outlines strategies for overcoming existing barriers, positioning borophene as a functional atom-thin layer in next-generation devices and sensors.