Comparative Density Functional Theory Insights Into B₁₆C₁₆ and Si₁₆C₁₆ Nanocages for Sensing Oil-Derived Fault Gases...

Oil-immersed electrical equipment, including power transformers and underground cables, generates fault-related decomposition gases such as C₂H₄, CO, and H₂S under abnormal operating conditions. Prompt and accurate detection of these toxic gases is critical for safe operations and system reliability. In this study, the adsorption and sensing behavior of these gases on boron carbide (B₁₆C₁₆) and silicon carbide (Si₁₆C₁₆) nanocages were investigated using density functional theory (DFT) at the B3LYP-D3/6-31G(d, p) level. Results show that gas adsorption is more effective on the BC nanocage than on SiC. The highest negative adsorption energies were recorded for C₂H₄ and CO on BC, reaching -80.274 and -84.580 kcal, for the C₂H₄_C4_BC and CO_C6_BC systems, respectively. H₂S adsorption on BC produced the lowest energy gaps of 1.867 and 1.914 eV in H₂S_C6_BC and H₂S_C4_BC, respectively, significantly enhancing electrical conductivity to 5.45 × 10¹² S/m and 5.40 × 10¹² S/m. BC-based systems consistently yielded positive sensing responses, while SiC-based systems showed mostly negative values. NCI and QTAIM analyses confirmed covalent and partially covalent interactions between the analytes and nanocages. These findings establish BC nanocages as superior candidates for detecting fault gases, offering theoretical guidance for next-generation sensors in power transformer diagnostics, renewable energy safety monitoring, and industrial hazard detection.