Density Functional Theory Study of Metal-Cluster-Modified Indium Selenide Monolayers for Transformer Oil Gas Sensing

Real-time detection of characteristic dissolved gases, specifically CO, H 2, C 2 H 2, and C 2 H 4, serves as a fundamental strategy for the early diagnosis of latent faults and comprehensive health assessment of oil-immersed power equipment. To address this industrial necessity, first-principles investigations based on density functional theory (DFT) were performed to evaluate the gas-trapping capabilities and sensing efficacies of InSe monolayers functionalized with Ag 3, Cu 3, and Ni 3 clusters. To achieve a profound understanding of the interfacial interaction mechanisms and gas-sensing performance, a comprehensive assessment of crucial physicochemical parameters was conducted, which encompassed optimized binding configurations, adsorption energies, band gaps ( E g ), differential charge densities (DCD), charge-transfer amounts ( Q T ), density of states (DOS), partial density of states (PDOS), frontier molecular orbitals, desorption times, and theoretical sensitivities. Our findings demonstrate that introducing metal clusters remarkably strengthens the interactions between the substrate and the target gases, endowing the functionalized monolayers with a vastly superior gas capture efficiency relative to that of bare InSe. Theoretical kinetic evaluations proved that the Ag 3 -decorated InSe configuration enables the efficient desorption of CO (5.42 s at 348 K), C 2 H 4 (8.83 s at 398 K), and C 2 H 2 (2.89 s at 398 K) under mild thermal conditions. Similarly, the Cu 3 –InSe platform facilitated the release of CO (1.221 s at 398 K) within comparable temperature ranges. In contrast, H 2 exhibits only weak physisorption on Ag 3 –InSe, Cu 3 –InSe, and Ni 3 –InSe, with low adsorption energies and negligible perturbation to the electronic structure, indicating that these materials are not suitable for H 2 sensing. Conversely, the Ni 3 –InSe complex exhibited overwhelmingly potent binding strength, retaining a rigid grip on CO, C 2 H 4, and C 2 H 2 across temperatures spanning from 298 to 498 K. Such distinct behaviors suggest that while Ag 3 –InSe and Cu 3 –InSe are highly promising for active sensor designs, Ni 3 –InSe serves as an ideal candidate for industrial gas scavenging.