A Theoretical Comparison on Pd-Doped MoSe2, WSe2, and MoSe2-WSe2 for Adsorption and Sensing of Dissolved Gases (H2, C2H2, and C2H4) in Transformer Oil

This study presents a comprehensive first-principles investigation into the gas adsorption and sensing characteristics of Pd-doped MoSe2, WSe2, and MoSe2-WSe2 systems for dissolved gas analysis applications in oil-filled transformers. Through theoretical simulations, we first establish and characterize three distinct Pd-doped systems, examining their structural stability, electronic properties, and gas interaction mechanisms with key typical gases (H2, C2H2, and C2H4). Our analysis reveals that the Pd@MoSe2-WSe2 heterojunction exhibits exceptional sensing performance, with calculated response values of −77.67% (H2), −95.98% (C2H2), and −96.88% (C2H4)—significantly surpassing the capabilities of both Pd-MoSe2 and Pd-WSe2 monolayers. The observed response hierarchy (C2H4 > C2H2 > H2) correlates directly with the degree of adsorption energy, charge transfer, and bandgap modification induced by gas adsorption. Finally, the reason for such enhancements are systemically analyzed. The findings not only position Pd@MoSe2-WSe2 as an outstanding candidate for condition evaluation in oil-filled transformers but also establish a structure–property relationship that uncovers the feasibility of a strategic heterojunction design to enhance the adsorption and sensing performances for typical gas species.