Advancements in theoretical and experimental investigations on diamane materials.

Technology-driven modern civilization demands new materials as its backbone. Consequently, based on intense research, a promising candidate, diamane, which is a two-dimensional (2D) form of diamond with a bilayer sp carbon nanostructure, has been proposed and recently achieved from bi-layer graphene (BLG) or few-layer graphene (FLG) through high-pressure technology or surface chemical adsorption. This material has been reported to possess a tunable bandgap, excellent heat transfer ability, ultralow friction, and high natural frequency, which can be a potential asset for cutting-edge technological applications, including quantum devices, photonics, nano-electrical devices, and even space technologies. In this review, following the history of the development of diamane, we summarize the recent theoretical and experimental studies on diamane in its pristine form and functionalized with substituents (H-, F-, Cl-, and OH-) in terms of atomic structure, synthesis strategies, physical properties, and potential technological applications. Also, the current challenges and future opportunities for the further development of diamane are discussed. As a young material with great potential but limited experimental research, there is still great space for its exploration.