Effect of biaxial strain and vacancy defects in 2D MoS2 monolayer for the sensing of nitrobenzene: A DFT investigation

Considering the increased release of toxic nitrobenzene (NB) molecules into the atmosphere, proposing a sensor material that could effectively remove it from the environment is essential. In this regard, we have investigated the NB adsorption performance of vacancy-defected (S, Mo and di S) and biaxially strained (−4 % to 4 %) MoS2 monolayers through density functional theory (DFT) simulations. Applying biaxial (tensile and compression) strain to the monolayer significantly increased the adsorption energy and charge transfer to −1.02 eV and 0.09 e, respectively, much greater than in the pristine case. The formation energy calculations verified the stability of (S, Mo, 2S) vacancy-defected MoS2 monolayer. The low formation energy of 3.3 eV suggests the ease of formation of MoS2 monolayer with single S vacancy. Introducing defects and strain improved the conductivity of the monolayer, thereby increasing the NB adsorption ability. The reasonable NB adsorption energy on the modified monolayer was due to the accelerated charge transfer and orbital interaction between the valence S 3p orbitals of MoS2 and 2p orbitals of O in NB. The recovery time of the strained and defective monolayers is the order of only a few seconds at 400 K, which is quite attainable. Therefore, this work put forth a more effective to improve the NB performance of the monolayer and can be a motivation for the further development of high-performance biomolecule sensors.