Engineering of the interactions of volatile organic compounds with MoS2

Abstract

We investigate the interactions between volatile organic compounds (VOCs, including ethanol, acetone and propanal) and pristine, defective and transition metal-functionalized MoS₂ using the first-principles method. The sensitivity of MoS₂-based chemical gas sensors could be drastically improved by transition metal functionalization. The VOCs exhibit physical adsorption on pure and sulfur-vacancy-defective MoS₂ but stronger chemisorption on transition metal (TM) (Fe, Co, Pd) functionalized MoS₂ together with larger adsorption energy and charge transfer. The band gaps of defective and transition metal functionalized MoS₂ are smaller than that of perfect monolayer MoS₂ and there are a few localized states inside. This also favors the adsorption of VOCs. The VOCs have the largest adsorption energies on the Fe functionalized MoS₂ substrate. The adsorption of VOCs will reduce the total magnetic moments of the Fe and Co functionalized MoS₂ substrates. Moreover the magnetic exchange coupling energies are variable in response to the adsorption of VOCs. The ferromagnetic coupling can be even reversed to anti-ferromagnetic coupling. This ferromagnetic to antiferromagnetic transition can be detected by a magnetic force microscope. Our work strongly suggests that MoS₂ is a compelling and feasible candidate as a magnetic sensor for VOCs.