A new 2D metallic K3Cl2 nanosheet as a promising candidate of NO2 gas sensor and capturer

Based on first-principles computations and global search method, we identify a new two-dimensional K3Cl2 nanosheet with unique structural and electrical properties. Formation energy and phonon spectrum calculations and ab initio molecular dynamics (AIMD) simulations confirm the stability of this predicted structure. The metallic character of the K3Cl2 can be maintained under tensile uniaxial and biaxial strains. The calculation demonstrates that K3Cl2 nanosheet can effectively detect NO2 molecules from the mixture of H-2, H2O, NH3, CO, NO, NO2 and CO2. The reason of the conversion from metal to semiconductor of K3Cl2 adsorbing different number of NO2 molecules might lie in the change of bonding/antibonding state of K-N, K-O and N-O bonds. Our calculated results show that K(3)Cl2 nanosheet is a promising NO2 gas sensor and capturer with high selectivity and sensitivity.