Boron-Based Two-Dimensional Nanosheets in Energy Devices

In the current scenario, 2D nanomaterials such as graphene, transition metal dichalcogenides, Mxenes, borophene, etc. play a significant role in the conversion of energy and its storage. Among these 2D nanomaterials, borophene shows versatile behavior because it consists of delocalized five-centered three-electron bonds, which leads to the metallic behavior of most borophene polymorphs. Borophene has become popular these days because the β12 phase of borophene delivers a considerable orbital overlap that gives a large electron density around the conduction level, which leads to a metallic behavior. The 2D boron nanosheet can be chemically functionalized by grafting, anchoring, etc., and exhibits remarkable properties like large surface area, high Young’s modulus, notable high Fermi velocity, flexibility, and optical properties that allow borophene to be employed in electronic and energy devices such as organic light-emitting diodes (OLEDs), fuel cells, storage batteries, oxygen evolution reaction (OER), oxidation–reduction reaction, and activating energy-rich small molecules. In this chapter, the recent advancements in the different polymorphs of borophene and its composites for energy conversion and storage devices are discussed, focusing on batteries, catalysis, and fuel cells for hydrogen storage.