Favourable adsorption and sensing properties of Pd-doped SnSSe monolayer towards H2 and C2H2 in the oil-immersed transformers

This work based on the first-principles theory simulates the Pd-doping behaviour on the SnSSe monolayer and the sensing properties of Pd-doped SnSSe (Pd-SnSSe) monolayer towards two dissolved gas species, namely H-2 and C2H2, aiming at exploring its potential as a chemical gas sensor to evaluate the operation status of the on-load tap-changer in the oil-immersed transformers. The Pd atom preferred to be doped on the Se-surface of the SnSSe monolayer with the formation energy (E-form) of 0.18 eV. The Pd-SnSSe monolayer behaves physisorption upon H-2 while chemisorption upon C2H2 with E-ad calculated as -0.20 and -0.87 eV, respectively. The BS results and the recovery property analysis reveal the strong potential of Pd-SnSSe monolayer as a C2H2 sensor with high sensitivity of -85.5% and good reusability with a recovery time of 510.1 s at room temperature. On the other hand, it is not suitable to explore the Pd-SnSSe monolayer as a reusable resistance-type sensor for H-2 detection, nor as an optical sensor for H-2 and C2H2 detections. This work gives a new insight into the Janus SnSSe monolayer for gas sensing application, which is beneficial for further exploration of SnSSe-based materials to be applied in the field of electrical engineering.