Theoretical Exploration of a Noble Metal-Decorated Black Arsenic–Phosphorus Monolayer as a Highly Sensitive Gas Sensor for Dissolved Gas Detection in Power Transformers

The aging or failure of power transformers poses a significant threat to both production and daily life, and employing characteristic dissolved gas detection offers an effective early warning system to mitigate such risks. In this study, we conducted first-principles simulations to investigate the adsorption and sensing characteristics of two-dimensional intrinsic and noble metal-decorated AsP monolayers toward four characteristic gases (C 2 H 4, H 2, C 2 H 2, and CO). Additionally, we conducted an in-depth analysis of the electronic structure and its impact on the sensing performance within the adsorption systems. The study demonstrates that the introduction of a noble metal improves gas behaviors, with the Ru-decorated AsP monolayer exhibiting particularly superior adsorption and sensing performances. At different temperatures, the H 2 /Ru-AsP adsorption system in transformer oil demonstrates excellent adsorption behavior. During the initial and later stages (from 350 to 900 K) of power transformer failure, the adsorption energy change is approximately −0.8 eV, and its desorption time is less than 0.5 s. Even in scenarios involving severe faults that result in equipment overheating and the subsequent generation of gases such as C 2 H 2 and C 2 H 4, the sensor demonstrates a consistent response time of less than 0.3 s. This work provides valuable research support for characteristic gas detection in the safe operation of power transformers.