Sensing response of Pd-modified Ti3C2O2 for dissolved gas molecules in power transformer oil

Mineral oil is the primary insulation dielectrics of power transformers. Multiple gas components can be generated due to the decomposition of insulation oil in response to the high electric field strength and high temperature. To detect trace gas components, such as C2H2, C2H4 and CH4, is beneficial to assess the healthy status of transformers and prevent the occurrence of faults. Although Ti3C2O2 shows potential in the sensing of polar gas molecules, the hydrocarbons gas molecules in insulating oil are difficult to be sensed by intrinsic Ti3C2O2. A Pd-doped Ti3C2O2 structure is proposed to increase the adsorption ability for the decomposition gas molecules in insulating oil. Firstly, the binding energy of Ti3C2O2 and Pd on four different doping sites was simulated. It is found that the substrate structure with Hole site doping has the finest stability. Secondly, the structure of the substrate with C2H2, C2H4 and CH4 gases adsorption was simulated. It indicates that C2H2 and C2H4 can form stable chemical bonds with the proposed substrate. In order to evaluate the conductivity and transfer electrons of the proposed substrate after the gas adsorption, the DOS, HOMO-LUMO, and DCD analysis were performed. The results show that after Pd doping, the adsorption energy of C2H2 and C2H4 is 5.076 and 4.750 times higher than that of the intrinsic Ti3C2O2, respectively. The transfer charge is 5.019 and 3.767 times higher than that of the intrinsic Ti3C2O2, respectively. Meanwhile, the work function analysis was performed to estimate the validation of proposed Pd-doped Ti3C2O2 as a FET-type gas sensor. The desorption time and the role of temperature on the regulation of desorption is analyzed at last. This work demonstrated that the Pd-doped Ti3C2O2 shows promising potential in improving the detection efficiency of hydrocarbons gas molecules.