Endowing bilayer transition-metal dichalcogenides (TMDs) with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom (DOFs). However, effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges. Herein, we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS₂ bilayer with substitutional doping of Co ion, by introducing sulfur vacancy (V_S) to modulate the interlayer electronic coupling. This strategy could transform the interlayer exchange interaction from antiferromagnetism (AFM) to ferromagnetism (FM), as revealed by the magnetic measurements. Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and V_S-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers, and also enhances the intralayer FM. Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional (2D) magnetic materials.

We report the Raman and photoluminescence spectroscopic analysis of layered MoS₂ under hydrostatic pressure up to ~ 30 GPa. Unlike previous studies, throughout this work, a special treatment is applied to submerge monolayer, bilayer, multilayer (~ 200 layers), and bulk MoS₂ samples directly into silicone oil without a supporting substrate in a diamond anvil cell, thereby eliminating possible interference from substrate–film contact. A thickness-dependent trend is observed for the 2H_c-to-2H_a phase transition: The transition pressure increases from 19.0 to 25.6 GPa as the system thickness is reduced from bulk to multilayer MoS₂; a further decrease in thickness to the bilayer structure increases the transition pressure to ~ 36 GPa, as predicted theoretically. This exceeds our measured pressure range, indicating the weakening of interlayer repulsive interactions as the MoS₂ film thickness is reduced. Our experiment also reveals a monotonic trend of Raman peak shifting vs. film thickness under applied pressure, suggesting that the Raman vibration modes are more responsive to external pressure in thinner films. The photoluminescence emission peak of the monolayer MoS₂ exhibits a blue shift under applied pressure at the rate of 23.8 meV·GPa^-1. These results show that the structural and optical properties of MoS₂ can be effectively modified by applying hydrostatic pressure.

We report a three-dimensional hierarchical ternary hybrid composite of molybdenum disulfide (MoS₂), reduced graphene oxide (GO), and carbon nanotubes (CNTs) prepared by a two-step process. Firstly, reduced GO–CNT composites with three-dimensional microstructuresare synthesized by hydrothermal treatment of an aqueous dispersion of GO and CNTs to form a composite structure via π–π interactions. Then, MoS₂ nanoparticles are hydrothermally grown on the surfaces of the GO–CNT composite. This ternary composite shows superior electrocatalytic activity and stability in the hydrogen evolution reaction, with a low onset potential of only 35 mV, a Tafel slope of ~38 mV·decade^-1, and an apparent exchange current density of 74.25 mA·cm^-2. The superior hydrogen evolution activity stemmed from the synergistic effect of MoS₂ with its electrocatalytically active edge-sites and excellent electrical coupling to the underlying graphene and CNT network.