Two-dimensional (2D) materials have recently received a great deal of attention due to their unique structures and fascinating properties,as well as their potential applications.2D hexagonal boron nitride (2D hBN),an insulator with excellent thermal stability,chemical inertness,and unique electronic and optical properties,and a band gap of 5.97 eV,is considered to be an ideal candidate for integration with other 2D materials.Nevertheless,the controllable growth of high-quality 2D h-BN is still a great challenge.A comprehensive overview of the progress that has been made in the synthesis of2D h-BN is presented,highlighting the advantages and disadvantages of various synthesis approaches.In addition,the electronic,optical,thermal,and mechanical properties,heterostructures,and related applications of 2D h-BN are discussed.