Atomic regulation to improve the sensing-performance of CoPc and NiPc monolayer toward chloromethane molecule: Insights from DFT calculations

Abstract

The development of a high-performance gas sensor for efficient detection of harmful chloromethane (CH3Cl) is of great importance to environmental monitoring and human health. Herein, the density functional theory (DFT) method was employed to compare the adsorption behaviors and electronic properties of CH3Cl on two-dimensional monometal modified phthalocyanines (CoPc, NiPc) and metal dimer modified phthalocyanines (CoTMPc and NiTMPc, TM = Ti∼Zn) surfaces. The studied results indicate that the CoPc and NiPc monolayers are not suitable as gas-sensitive materials for the detection of CH3Cl molecule due to their weak adsorption ability and low sensitivity. However, the adsorption strength and electronic properties of single-layer CoTMPc and NiTMPc towards CH3Cl can be effectively regulated through the synergistic effect of bimetallic species. Among them, the CoVPc, Co2Pc, NiVPc and NiZnPc monolayers exhibit moderate affinity for CH3Cl molecule, with the adsorption energies of −0.84 eV, −0.62 eV, −0.89 eV and −0.54 eV, respectively. The microscopic interaction mechanisms between CH3Cl molecule and bimetallic phthalocyanine monolayers are revealed through the analyses of total charge density, charge density difference and density of states. Furthermore, significant changes in bandgap are observed for Co2Pc and NiZnPc upon CH3Cl adsorption, while CoVPc and NiVPc monolayers exhibit noticeable variations in magnetic moments, indicating their high sensitivity towards CH3Cl. Considering the balance of adsorption strength, sensitivity and recovery time, the CoVPc, Co2Pc, NiVPc and NiZnPc monolayers are regarded as a great potential as gas-sensitive materials for recyclable CH3Cl gas sensors.