First-principles insights into Pd and Rh functionalization of Janus Ga2SSe monolayers for enhanced sensing of toxic industrial gases

Abstract

The release of hazardous gases from industrial activities constitutes a significant risk to both ecological stability and public well-being, underscoring the critical need for advanced sensors enabling continuous, real-time monitoring. This study utilizes first-principles calculations to systematically investigate the adsorption behavior of six industrial toxic gases (NO, NO₂, SO₂, CO, Cl₂, NH₃) on both pristine and Pd/Rh-functionalized Ga₂SSe (Pd-Ga₂SSe and Rh-Ga₂SSe) monolayers, with comprehensive analysis of charge transfer, charge density difference, density of states, band structure, and recovery time. The results show that the pristine Ga₂SSe monolayer exhibits weak physisorption towards the target gases, rendering it unsuitable for effective sensing. Conversely, functionalization with Pd and Rh atoms significantly enhances the adsorption capability of the Ga₂SSe monolayer for these gases. Specifically, NO, NO₂, SO₂, CO, and Cl₂ demonstrate strong chemisorption on both Pd-Ga₂SSe and Rh-Ga₂SSe surfaces, characterized by adsorption energies typically more negative than −0.9 eV. This strong interaction is further corroborated by analyses of charge transfer, charge density difference, and density of states. Furthermore, the Pd-Ga₂SSe and Rh-Ga₂SSe monolayers exhibit high sensitivity toward NO, NO₂, SO₂, Cl₂, and NH₃, as evidenced by substantial changes in their band gap or work function. Calculated recovery times suggest that Pd-Ga₂SSe can be a reusable gas-sensitive material for Cl₂ at 348 K and 398 K with recovery times of 10.71 s and 0.24 s. Similarly, Rh-Ga₂SSe can be a reusable gas sensor with sensitivity toward NH₃ and Cl₂ at 398 K. Consequently, Pd- and Rh-decorated Ga₂SSe monolayers have great potential as novel gas-sensitive candidate materials for efficient monitoring of inorganic toxic gases in industrial environments.