A DFT Study of CO, H2, C2H2 and CH4 Adsorption onto SnS2-Based Monolayers: Favorable Sensitivity and Selectivity by Doping Single Pd or Pt Atoms

This study applied density functional theory (DFT) to investigate gas-sensitive devices based on Pt- and Pd-doped SnS2 monolayers, exploring their adsorption and sensing performance on four characteristic gases generated under normal operating or fault conditions of transformer oil. The adsorption behaviors and underlying sensing mechanisms of four gases on pristine and modified SnS2 were systematically elucidated. The results reveal that Pt/Pd incorporation triggers a transition from weak physisorption to robust chemisorption. Compared to intrinsic SnS2, the decorated monolayers exhibit dramatically augmented adsorption energies and accelerated interfacial charge transfer for all target molecules. Crucially, noble metal modification fundamentally modulates the electronic structure of the SnS2 lattice, endowing the material with exceptional recognition specificity for distinguishing different gas species. These theoretical insights establish Pt- and Pd-SnS2 as highly promising candidates for advanced DGA sensors, providing a robust materials design strategy for the condition monitoring of critical electrical infrastructure.