On the basis of first-principles plane-wave calculations, we examine the adsorption and diffusion of lithium on the hexagonal MoS2(1–x)Se2x monolayers with variation of x for 0.00, 0.33, 0.50, 0.66, and 1.00. We find that the lowest energy adsorption positions of Li adatom is at the top site of Mo atom in both MoS2 and MoSe2 monolayers, while Li moves through the MoS bond for MoS2(1–x)Se2x . While bare MoS2(1–x)Se2x compounds are nonmagnetic semiconductor and its energy band gap varies with x, they can be metallized by Li adsorption. NEB calculation results show that their energy barriers make them suitable for using in electrode materials. The lithium adsorption energy is sensitive to the external strain, when we elongate the lattice constants, the adsorption energy decreases quickly. We also examine the penetration energy barrier for single lithium atom to pass through the MoS2(1–x)Se2x monolayers, this barrier is decreasing from ∼2.5 eV to ∼1.3 eV with increasing selenium concentration.

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Recent studies show that several metal-oxides and dichalcogenides (MX2), which exist in nature, can be stable in two dimensional (2D) form and each year several new MX2 structures are explored. The unstable structures in H (hexagonal) or T (octahedral) forms can be stabilized through Peierls distortion. In this paper, we propose new 2D forms of RuS2 and RuSe2 materials. We investigate in detail the stability, electronic, magnetic, optical, and thermodynamic properties of 2D RuX2 (X=S, Se) structures from first principles. While their H and T structures are unstable, the distorted T structures (T ′ -RuX2) are stable and have a nonmagnetic semiconducting ground state.The molecular dynamic simulations also confirm that T ′ -RuX2 systems are stable even at 500 K without any structural deformation. T ′ -RuS2 and T ′ -RuSe2 have indirect band gaps with 0.745 eV (1.694 eV with HSE) and 0.798 eV (1.675 eV with HSE) gap values, respectively. We also examine their bilayer and trilayer forms and find direct and smaller band gaps. We find that AA stacking is more favorable than AB configuration. The obtained new 2D materials can be good candidates with striking properties for applications in semiconductor electronic, optoelectronic devices, and sensor technology.