Enhanced Adsorption Properties of Noble Metal Modified MoS2/WS2 Heterojunctions

Abstract

MoS₂/WS₂ in-plane heterojunction is constructed using density functional theory (DFT), and its adsorption properties for different gas molecules (CO, CO₂, NO₂, H₂S, SO₂, and SO₃) are analyzed. Results indicate that the heterojunction exhibits excellent selection toward S-series gas molecules (H₂S, SO₂, and SO₃), particularly SO₃. The adsorption energy is determined to be −3.67 eV. Then, the adsorption properties of the heterojunction are further improved by noble metal (Ag, Au, and Pt) modification. Noble metal atoms alter the surface potential energy of the heterojunction, resulting in stronger adsorption activity. For instance, the binding energies of noble metals in the Ag-MoS₂/WS₂, Au-MoS₂/WS₂, and Pt-MoS₂/WS₂ systems are −1.03, −1.04, and −2.76 eV, respectively. Additionally, there has been a significant alteration in their bandgaps. Notably, the bandgap of Pt-MoS₂/WS₂ has decreased to 1.42 eV (24.16%), which is the most pronounced change. Then, the charge density difference and density of states of noble metal-modified MoS₂/WS₂ heterojunction adsorbed SO₃ are analyzed. The results demonstrate that the adsorption capacity of a noble metal-modified system for SO₃ is enhanced. Finally, raising the temperature can accelerate gas molecule desorption from the system. Combining all calculation results, Ag-MoS₂/WS₂ in-plane heterojunction can be used as a candidate gas-sensitive material for detecting SO₃ at room temperature (300 K). The Pt-MoS₂/WS₂ in-plane heterojunction is demonstrated to possess effective adsorbent properties for trapping SO₃ gas molecules at room temperature. This provides a new idea and theoretical basis for gas sensor development.