Adsorption and Sensing Mechanism of Late Transition Metal Doped MoTe2 Monolayers for Dissolved Gas Analysis in Transformer Oil: A First-Principles Study

Equipment faults in power transformers can be detected by analyzing the dissolved gas in their internal insulation oil. In this study, the adsorption behavior and sensing properties of several characteristic dissolved gases (H2, CO, C2H2, and C2H4) on pristine and late transition metal (TM) (Fe, Co, Ni, and Cu)-doped MoTe2 were investigated using density functional theory (DFT) calculations. The adsorption energy, charge transfer (
${Q}_{T}{)}$
, charge density difference (CDD), band structure, density of states (DOS), work function, and occupation function were compared to understand the gas adsorption behavior and electronic properties. The results demonstrate that TM-MoTe2 monolayers exhibit excellent sensing properties for H2, CO, C2H2, and C2H4 compared to pristine MoTe2. Among the four TM atoms, Co-doped MoTe2 shows the highest increase in adsorption energy for H2, CO, C2H2, and C2H4. The DOS analysis reveals clear hybridization between the molecular orbitals of the adsorbed gas molecules and the TM atomic orbitals for CO, C2H2, and C2H4 adsorption systems, indicating strong chemical interactions between these three gases and TM-MoTe2 surfaces. Moreover, the Co-MoTe2 surface exhibits superior sensitivity toward the adsorption of these four gas molecules. The introduction of TM doping shows a significant enhancement in adsorption selectivity, and TM-MoTe2 demonstrates the most dominant selective adsorption of CO molecules. This study provides valuable theoretical insights for the design of a new gas sensor aimed at detecting dissolved gases.