Effect of strain on structure and electronic properties of monolayer C₄N₄

The first-principles calculations are performed to examine structural, mechanical, and electronic properties at large strain for a monolayer C₄N₄, which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier. Our results show that the ideal strengths of C₄N₄ under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28, respectively. The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C₄N₄. The orderly bond-rearranging behaviors under the weak tensile loading path along the 100 direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition. The present results enrich the knowledge of the structure and electronic properties of C₄N₄ under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.