Pd-Decorated WTe₂ Monolayer as a Favorable Sensing Material toward SF₆ Decomposed Species: A DFT Study

Based on density functional theory, this work first investigates the Pd-decorating property on the pristine WTe₂ monolayer and then simulates the adsorption performance of a Pd-decorated WTe₂ (Pd-WTe₂) monolayer on SO₂ and SOF₂ molecules, in order to explore its sensing potential for SF₆ decomposed species. It is found that the Pd atom can be stably anchored on the top of the W atom of the WTe₂ monolayer with a binding energy of -2.43 eV. The Pd-WTe₂ monolayer performs chemisorption on SO₂ and SOF₂, with adsorption energies of -1.36 and -1.17 eV, respectively. The analyses of the band structure and density of states reveal the deformed electronic property of the WTe₂ monolayer by Pd-decoration, as well as that of the Pd-WTe₂ monolayer by gas adsorption. The bandgap of the Pd-Wte₂ monolayer is increased by 1.6% in the SO₂ system and is decreased by -3.9% in the SOF₂ system, accounting for the sensing response of 42.0 and -56.7% for the detection of two gases. Moreover, the changed work function (WF) in two gas systems in comparison with that of the pristine Pd-WTe₂ monolayer suggests its potential as a WF-based gas sensor for sensing two gases as well. This paper uncovers the gas sensing potential of the Pd-WTe₂ monolayer to evaluate the operation status of SF₆ insulation devices, which also illustrates the strong potential of WTe₂-based materials for gas sensing applications in some other fields.