Ab-Initio Study ofRu<i>_n</i> and Rh<i>_n</i> (<i>n</i> = 1–3)Nanoclusters on Monolayer MoSSe for Sensing Industrial Toxic Gases

This study uses density functional theory (DFT) to explore the adsorption behavior and properties of MoSSe doped with Ru<i>_n</i> and Rh<i>_n</i> (<i>n</i> = 1–3) transition metal clusters, aiming to improve its adsorption performance for industrial toxic gases (Cl₂, NH₃, and SO₂). The structural characteristics of the doped system were examined using parameters such as binding energy (<i>E</i>_b), charge transfer (<i>Q</i>_t), deformation charge density (DCD), and band gap (<i>B</i>_g). Compared to the intrinsic MoSSe <i>B</i>_g (1.598 eV), doping with Ru<i>_n</i> and Rh<i>_n</i> clusters significantly reduces the <i>B</i>_g, resulting in a more compact electronic structure, especially in the Ru–MoSSe system, where the <i>B</i>_g declines to 0.137 eV. During doping, metal clusters obtain electrons from the substrate, which reduces the substrate band gap and improves its conductivity. A deeper evaluation of adsorption energy (<i>E</i>_a), charge transfer (<i>Q</i>_t), DCD, and density of states (DOS) was performed to assess the adsorption and detection capabilities of the doped materials for the gas species of interest. The findings indicate that the modified substrates exhibit the highest adsorption affinity for the gases in the following sequence: Cl₂ > SO₂ > NH₃. However, in the Ru₃ and Rh-doped systems, the order changes to Cl₂ > NH₃ > SO₂. Analysis of the work function, sensitivity, and recovery time reveals the adsorption and detection properties of the modified substrates. Among them, Ru–MoSSe exhibits the highest sensitivity to Cl₂, reaching 1.61 × 10⁵. At ambient temperature, the recovery times for SO₂ on Ru₃–MoSSe and Rh–MoSSe are 3.32 × 10^–2 s and 1.94 s, respectively. This research offers a theoretical basis for designing effective sensors to detect industrially toxic gases.