Computational discovery of diverse functionalities in two-dimensional square disulfide monolayers: auxetic behavior, high curie temperature ferromagnets, electrocatalysts, and photocatalysts

By means of systematic density functional theory (DFT) computations, we identified 12 stable two-dimensional (2D) disulfide monolayers featuring a square lattice from a pool of 68 candidate monolayers. Our screening process comprehensively assessed their thermodynamic, dynamic, mechanical, and thermal stabilities. These 12 stable monolayers (S-XS2 with X = Si, Ge, Sn, Pb, Ti, V, Cr, Mn, Zr, Mo, Re, and Os) all exhibit low in-plane Young's modulus (25.30-96.09 Nm-1). Notably, four S-XS2 (X = Si, Ge, Sn, and Pb) monolayers possess negative Poisson's ratios (NPRs). The magnetic and electronic properties vary across the monolayers, with S-ReS2 and S-OsS2 being nonmagnetic and metallic, S-MoS2 being antiferromagnetic and metallic, and S-SiS2, S-GeS2, S-SnS2, S-PbS2, S-ZrS2, and S-TiS2 being nonmagnetic and semiconducting (bandgaps ranged between 1.59 and 2.79 eV). The S-VS2 monolayer exhibits ferromagnetic half-semiconductor behavior, while S-CrS2 and S-MnS2 are ferromagnetic half-metals. The carrier mobilities of the seven semiconducting monolayers range widely (0.20-17 068.47 cm2 V-1s-1), and hole mobility could be controlled through uniaxial strains in S-ZrS2, S-TiS2, and S-VS2. Additionally, certain monolayers (S-XS2 with X = V, Cr, and Mn) have high Curie temperatures and magnetic anisotropy energies. Two semiconducting monolayers (S-XS2 with X = Si and Ge) are promising candidates for photocatalyzing water splitting, and the metallic or half-metallic S-ReS2 and S-OsS2 can boost the electrochemical hydrogen evolution reaction. This work not only adds novel members to the family of 2D materials, but also provides theoretical guidance for further explorations to both experimental and theoretical communities. By means of systematic density functional theory (DFT) computations, we identified 12 stable two-dimensional (2D) disulfide monolayers featuring a square lattice from a pool of 68 candidate monolayers.

Automated summary

By using density functional theory (DFT) computations, we have identified 12 stable two-dimensional disulfide monolayers with low Young's modulus and different magnetic and electronic properties. Some of these monolayers have potential applications in photocatalysis and electrochemical hydrogen evolution reaction.