First-Principles Investigation of HCHO and C2H3Cl Adsorption on Rh-Doped PdS2 Monolayers

This paper examines the gas sensing properties of Rh single-atom functionalized PdS2 monolayers in the adsorption and detection of harmful VOC gas molecules, that is, Formaldehyde (HCHO) and vinyl chloride (C2H3Cl). Despite structural stability, pristine PdS2 has low surface reactivity, which restricts the exposure of the material to VOC species. Sulfur vacancy defect was incorporated as a site where single Rh atom doping was to be formed to enhance the surface activity to form the system, Rh-PdS2. The adsorption energy of the Rh atom to the vacancy site is very strong (at −0.856 eV), indicating a high stability and absence of dopant clustering. Rh functionalization will greatly activate PdS2, creating impurity gaps and reducing the band gap to 0.191 eV. Both gases are found to be stabilized smoothly through chemisorption, which is proven through adsorption analysis. HCHO has less interaction (−1.15 eV) and minimal electronic change, which has a charge transfer (0.025 e) and a bandgap (0.194 eV). C2H3Cl, on the other hand, adsorbs more intensely (−1.49 eV) with an order of magnitude greater charge transfer (0.224 e), and causes a strong band-gap transition to (0.344 eV), giving a clear mechanism of selective Gas detection. Density of states (DOS) analysis also aids in demonstrating redistribution of electrons states on the redistribution of electrons close to the Fermi level caused by adsorption. Altogether, the vacancy engineering of Rh single-atom functionalization offers a control mechanism of enriching PdS2 to VOC sensing-associated applications and offers it as a prospect of next-generation VOC sensing devices.