Atomic-level insights into sensing performance of toxic gases on the InSe monolayer decorated with Pd and Pt under humid environment

The timely detection and monitoring of toxic gases are crucial for preserving the ecological environment and preventing their adverse effects on human health. In this study, we investigate the adsorption characteristics and sensitivity performance of Pd- and Pt-decorated InSe monolayers, referred to as Pd-InSe and Pt-InSe, towards five toxic gases (CO, NO, NH₃, H₂S, and SO₂) using first-principle calculations. The results show that the doping of Pd and Pt atoms significantly improves the conductivity, adsorption capabilities, and sensing properties of InSe monolayer to these toxic gases. Both Pd-InSe and Pt-InSe monolayers exhibit chemical adsorption of CO, NO, NH₃, and H₂S, with adsorption energies ranging from –0.56 eV to –1.04 eV, leading to noticeable changes in the bandgap (8.84 % ∼ 31.03 %). Furthermore, the CO/Pd-InSe and H₂S/Pt-InSe systems demonstrate excellent sensitivity, with high sensing response values of 1.54×10⁴ and 66.20, respectively, and their sensitivity remains unaffected under humid environments. Importantly, Pt-InSe exhibits a fast recovery time of 0.05 s at 298 K, making it highly promising for the recyclable detection of H₂S at room temperature. In contrast, Pd-InSe can be utilized as a reusable gas sensor for CO at 448 K with a good recovery time of 0.5 s. This work can provides theoretical guidance for the design and fabrication of InSe-based gas sensors for the detection of toxic gases.