NO2 capture on graphene/WSe2 heterostructure with high sensitivity and selectivity modulated by external electric field

Abstract

The adsorption performance of ten gas molecules (H2, N2, O2, CO, CO2, H2O, NO, NO2, SO2 and CH4) on graphene/WSe2 heterostructure is studied by means of first-principles calculations. The results show that gas molecules are physisorbed on the heterostructure surface owing to the weak interface interaction between gas molecules and graphene/WSe2. Meanwhile, NO2 has the strongest interactions with the graphene/WSe2 heterostructure among these gas molecules, suggesting the heterostructure has the highest selectivity towards NO2. Moreover, NO2 behaves as an electron acceptor and attracts electrons from graphene/WSe2 heterostructure, resulting in the reduction of Schottky barrier height of the heterostructure. Further, the controlled external electric field regulates the adsorption properties of the gas-graphene/WSe2 system in terms of the adsorption energies, band structures, and charge transfer. It is found that the sensitivity of NO2 on graphene/WSe2 heterostructure can be enhanced under large positive electric field (E = +0.5 V/Å), which induced by the charge redistribution between gas and the heterostructure. Our work will provide a preference to design the WSe2-based sensors with high sensitivity and selectivity.