Ni-Decorated PtS(2) Monolayer as a Strain-Modulated and Outstanding Sensor upon Dissolved Gases in Transformer Oil: A First-Principles Study

[Image: see text] The first-principles theory is conducted in this paper to investigate the adsorption and electronic properties of a Ni-decorated PtS(2) (Ni-PtS(2)) monolayer upon two dissolved gas species (CO and C(2)H(2)) in the transformer oil, thus illustrating its sensing performance and related potential to evaluate the working condition of the oil-immersed transformers. We then highlight the effect of the biaxial strain on the configuration, charge transfer, and bandgap of the adsorbed systems to expound its potential as a strain-modulated gas sensor. Results indicate that the Ni-PtS(2) monolayer undergoes chemisorption upon two species, with an E(ad) value of −1.78 eV for the CO system and −1.53 eV for the C(2)H(2) system. The reduced bandgap by 0.164 eV (20.05%) in the CO system and 0.047 eV (5.74%) in the C(2)H(2) system imply the large feasibility of the Ni-PtS(2) monolayer to be a resistance-type sensor for CO and C(2)H(2) detection, which is also verified by the I–V analysis of these systems. Besides, the applied biaxial strain can exert geometric activations on the Ni-PtS(2) monolayer, and specifically, the compressive force can further reduce the bandgap in two systems, thus promoting its sensing response upon two gases. Our work is meaningful to broaden the exploration of noble transition metal dichalcogenides for gas sensing.