First-principles investigation of Pd modified HfTe2 monolayer membranes: Detection of dissolved gas in transformer oil

Detecting the fault characteristic gases in insulating oil of oil-immersed transformers is of significant importance for the stable operation of power systems. In this work, based on first-principles calculations, we constructed pristine HfTe₂ and Pd modified HfTe₂ structures. Twelve adsorption configurations for CO, CO₂, CH₄, C₂H₂, C₂H₄, and H₂ gas molecules on the surfaces of pure HfTe₂ and Pd-HfTe₂ were developed by means of geometry optimization. From a number of angles, including adsorption energy, density of states, electron density, frontier molecular orbital theory, sensitivity, recovery time, and work function, we thoroughly investigated the adsorption characteristics and gas-sensing processes of these adsorption systems. The results demonstrate that Pd-HfTe₂ significantly enhances the adsorption performance for CO, CO₂, and C₂H₄, with adsorption energies reaching −1.425 eV, −0.786 eV, and −0.816 eV, respectively. Furthermore, the recovery times for CO₂ and C₂H₄ at 298 K are 19.22 s and 63.20 s, indicating that these gases can be rapidly desorbed from the Pd-HfTe₂ surface at room temperature. Compared with other two-dimensional materials, Pd-HfTe₂ holds promise as a low-power gas sensor for detecting characteristic gases like CO₂ and C₂H₄ and as a solid adsorbent material for cleaning CO gas. Theoretical advice for the construction of HfTe₂ sensors that can detect dissolved characteristic gases in oil is provided by the simulation results described in this study.