As a new paradigm of material science, two-dimensional (2D) heterostructured composites have attracted extensive interests because of combining the collective advantages and collaborative characteristics of individual building blocks. Molybdenum disulfide (MoS₂) has demonstrated great promise as a low-cost substitute to platinum-based catalysts for electrochemical hydrogen production. However, the broad adoption of MoS₂ is hindered by its limited number of active sites and low inherent electrical conductivity. One of the promising methods to further activate MoS₂ is coupling engineering. Here, we demonstrate for the first time the synthesis of 2D MXene-MoS₂ nanocomposites through chemical vapor deposition (CVD) approach, thus leading to precise design in structure type and orientation. The computational results show that nanocomposites have metallic properties. Owing to their unique 2D/2D structure, MXene-MoS₂ nanocomposites exhibit more active catalytic sites, resulting in higher electrochemical performance, as inherited from parent excellent characteristics, and a much lower overpotential of ~ 69 mV at a current density of 10 mA·cm⁻² is achieved. This work paves the way to employ CVD method by coupling engineering to construct 2D nanocomposites for energy storage applications.

Regarding the reverse process of materials growth, etching has been widely concerned to indirectly probe the growth kinetics, offering an avenue in governing the growth of two-dimensional (2D) materials. In this work, interface-driven anisotropic etching mode is demonstrated for the first time to be generally applied to 2D heterostructures. It is shown that the typical in-plane graphene and hexagonal boron nitride (h-BN) heterostructures follow a multi-stage etching behavior initiated first along the interfacial region between the two materials and then along edges of neighboring h-BN flakes and finally along central edges of h-BN. By accurately tuning etching conditions in the chemical vapor deposition process, series of etched 2D heterostructure patterns are controllably produced. Furthermore, scaled formation of graphene and h-BN heterostructures arrays has been realized with full assist of as-proposed etching mechanism, offering a direct top-down method to make 2D orientated heterostructures with order and complexity. Detection of interface-driven multi-staged anisotropic etching mode will shed light on understanding growth mechanism and further expanding wide applications of 2D heterostructures.