DFT investigation of gas adsorption and electronic modulation on Cd- and Zn-decorated PdSe2 monolayers for sensor applications to NO, CO, and NO2

Abstract

This study employs density functional theory (DFT) calculations to explore the interaction of NO, CO, and NO₂ gases with pristine and transition metal-decorated PdSe₂ monolayers functionalized with Cd and Zn atoms. The investigation reveals that surface decoration significantly enhances the adsorption strength and modifies the electronic properties of the PdSe₂ monolayer compared to its pristine form. Cd and Zn atoms preferentially occupy energetically favorable sites on the PdSe₂ surface, facilitating stronger binding and charge transfer with the adsorbed gas molecules. Among the gases examined, NO and CO adsorb preferentially via their nitrogen and carbon atoms, respectively, directly at the metal centers with moderate adsorption energies and induce notable bandgap narrowing, reflecting enhanced interaction and sensor response potential. NO₂ exhibits the highest adsorption energy and pronounced impact on the band structure, suggesting potential catalytic activity alongside sensing capabilities. Electronic structure analyses highlight notable bandgap reductions and charge redistribution upon gas adsorption, which correlate with enhanced electrical conductivity and sensing response. Furthermore, calculated work function shifts upon gas adsorption indicate favorable modulation of Schottky barrier heights at metal–semiconductor interfaces, signifying the potential for sensitive and selective Schottky-type gas sensors based on Cd- and Zn-decorated PdSe₂ monolayers. These findings indicate that Cd- and Zn–PdSe₂ monolayers present promising platforms for sensitive and selective detection of hazardous gases like NO, CO, and NO₂. The results provide insights into the design of efficient resistive and Schottky-type gas sensors with improved performance for environmental monitoring applications.