Density Functional Theory Calculations of the Stability, Electronic Structure, and Magnetism of ReS2 Nanoribbons: An Emerging Material for Electrocatalytic Reactions

In the form of finite-width nanoribbons, two-dimensional nanomaterials have interesting structural, electronic, and magnetic properties due to their edges. MoS2 nanoribbons have been widely explored for their applications in sensors and electrocatalytic materials. In this paper, we investigate nanoribbons of ReS2 for their edge geometry, stability, electronic structure, and magnetism using density functional theory. We find that monolayer ReS2, a nonmagnetic direct band gap semiconductor, yields three types of stable edge geometry for nanoribbons upon cleavage. One of these has an armchair-like edge structure, while the other two are of the zigzag type, and these three are respectively named α, β, and γ nanoribbons of ReS2. We analyze the stability using the formation energy of these ribbons and study its dependence on the ribbon width. Some nanoribbons considered here show magnetism due to unsaturated valency at the edges. The ordering of edge atom spins leads to different kinds of magnetic states. The electronic structure of the ribbons shows interesting metallic and semiconducting behavior due to states arising out of broken bonds. Passivation of the edge Re and S atoms with hydrogen leads to better stability. The electronic state after passivation sensitively depends on the structure. ReS2 nanoribbons are unique among other transition-metal dichalcogenide nanoribbons due to their edge structure and interesting electronic and magnetic properties, which can lead to wide applications in the field of electrochemical catalysis.