Layer-by-Layer Self-Assembly Strategies of Atomically Thin Two-Dimensional Nanomaterials: Principles, Methods, and Functional Applications

Two-dimensional (2D) layered materials are an indispensable cornerstone of modern industry, which harnesses their strengths and creativity for energy, catalysis, sensors, and many other fields. Nowadays, materials science has transitioned from single-component substances to multicomponent composites, and how to efficiently construct multifunctional layered composites with controllable and stable structures has become a research hotspot. Among many available preparation techniques, the layer-by-layer (LbL) self-assembly technology is one of the most efficient strategies, which utilizes the noncovalent weak intermolecular forces to achieve stable binding of different components and thus exhibits extensive suitability compared with traditional methods. Precise molecular-level control of the structure and properties of LbL-assembled composites can be achieved through the selection of assembly units and the design of the assembly sequence. Benefiting from these merits, LbL-assembled laminated composites have been widely used in energy conversion and storage, optoelectronic and magnetic devices, drug delivery, sensors, separation membranes, and so on. In this review, we summarize the recent advances in the current mainstreams of LbL assembly technology, including the van der Waals (vdW) assembly, electrostatic assembly, Langmuir–Blodgett (LB) assembly, and hydrogen-bonded assembly. Moreover, a systematic review and perspective are provided not only on the applications of water electrolysis, lithium-ion batteries, optoelectronics, and magnetic devices but also on the existing challenges and future directions for LbL assembly.