Niobium doped MoS2 with double S vacancy defects as gas sensing materials for sulfur-containing gas molecules: A first-principle investigation

Abstract

Electronic and adsorption properties of MoS2 with single S vacancy (MoS2 (VS)) and double S vacancy defects (MoS2 (V2S)) toward three gas molecules (SO2, H2S and SO3) are studied based on the density functional theory (DFT). The adsorption energy, energy band, density of states (DOS), charge density difference (CDD), highest occupied molecule orbital/lowest unoccupied molecule orbital (HOMO/LUMO) and work function are calculated. The results indicate that pristine MoS2 is not suitable for high-sensitivity sensing detection for SO2, H2S and SO3, which exhibits weak adsorption forces. At the same time, MoS2 (VS) and MoS2 (V2S) are still physical adsorption for three gas molecules. Therefore, the synergistic effect of double S vacancies and Nb doping on the adsorption characteristics of MoS2 is studied. The results show that the adsorption type of both MoS2 (V2S)/2Nb and MoS2 (V2S)/3Nb for H2S is changed from physical adsorption to chemical adsorption. The corresponding physical mechanism is discussed.