Theoretical study of 2D PbSe/Bi₂Se₃ heterojunctions as gas sensors for the detection of SO₂ and Cl₂

Abstract In this paper, we construct a two-dimensional PbSe/Bi 2 Se 3 van der Waals heterojunction to study the adsorption of Cl 2 and SO 2 by this heterojunction. Based on the help of Bader charge, charge density difference diagram, and electron localization function, we find the following conclusions. Among the six configurations, three meet the requirements for semiconductor gas sensor detection materials, namely α -PbSe-Bi 2 Se 3 , β -PbSe-Bi 2 Se 3 , and Bi 2 Se 3 - γ -PbSe. The Bi surface of the configuration α -PbSe-Bi 2 Se 3 does not break the Cl-Cl bond in the Cl 2 molecule after the adsorption of Cl 2 , and the band gap of the adsorbed material is reduced by 73.1%. The band gap of the Pb surface of the α -PbSe-Bi 2 Se 3 , β -PbSe-Bi 2 Se 3 and Bi 2 Se 3 - γ -PbSe configurations change significantly after the adsorption of SO 2 , directly changing from a narrow band gap to a metallic material with a low adsorption energy and easy desorption of SO 2 from the adsorbed material. Therefore, the two-dimensional PbSe/Bi 2 Se 3 van der Waals heterojunction has the potential to become a core detection material for Cl 2 and SO 2 gas sensors.