Conformal Two-Dimensional Materials: Preparation and Applications

Conformal two-dimensional materials refer to an atomically-thin layered material that can closely adhere on the surface of any substrate. It is tightly coated on the substrate surface like a thin film, along with the contour of the substrate surface, and thus forms a new type of functional composite structural material. This conformal structural material not only inherits the original surface morphological characteristics of the substrate, but also endows the substrate with novel physical properties of two-dimensional materials to achieve new functions and stimulate new physical and chemical effects under the interaction between two-dimensional materials and the substrate. The introduction of special substrate structures can enable two-dimensional materials to transcend the limitations of two-dimensional space. Combining the planar structure of two-dimensional materials with the arbitrary curved structure of the substrate is an important way to enhance interactions between two-dimensional materials and the surrounding environment, greatly expanding the application fields of two-dimensional materials, and may even achieve the killer applications. On the basis of proposing the concept of conformal two-dimensional materials, this article first elucidates the mechanism of conformal growth of two-dimensional materials, reveals the influence of substrate features and structures on the conformal growth and conformity of two-dimensional materials, as well as explores the thermodynamic factors and spatial equilibrium conditions that affect material growth behaviors. Second, it classifies and summarizes current progress on the preparation methods, properties, and applications of conformal two-dimensional materials represented by open and confined structures of substrates. Finally, the challenges and future development directions in this field are discussed.