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

In this paper, we construct a two-dimensional PbSe/Bi2Se3 van der Waals heterojunction to study the adsorption of Cl-2 and SO2 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 & alpha;-PbSe-Bi2Se3, & beta;-PbSe-Bi2Se3, and Bi2Se3-& gamma;-PbSe. The Bi surface of the configuration & alpha;-PbSe-Bi2Se3 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 & alpha;-PbSe-Bi2Se3, & beta;-PbSe-Bi2Se3 and Bi2Se3-& gamma;-PbSe configurations change significantly after the adsorption of SO2, directly changing from a narrow band gap to a metallic material with a low adsorption energy and easy desorption of SO2 from the adsorbed material. Therefore, the two-dimensional PbSe/Bi2Se3 van der Waals heterojunction has the potential to become a core detection material for Cl-2 and SO2 gas sensors.