Comparative analysis of adsorption and gas-sensing performance in metal oxide-functionalized GaN nanotubes for...

The eco-friendly gas C₄F₇N has emerged as a promising alternative to SF₆ for online monitoring in gas-insulated switchgear (GIS) high-voltage (HV) electrical systems, but partial discharges-an inherent issue in such environments-cause C₄F₇N decomposition, generating byproducts like CF₃CN. This study employs first-principles calculations to systematically investigate the adsorption and electronic properties of metal oxide-modified GaN nanotubes (GaNNTs) (CuO, ZnO, Ag₂O, CrO₂) toward CF₃CN, analyzing key parameters such as band gaps, density of states (DOS), differential charge density (DCD), and molecular orbital interactions. The results demonstrate that metal oxide modification enhances the conductivity of GaNNTs by significantly reducing their band gaps compared to pristine GaNNTs, with decreases of 40.13% (CuO), 67.97% (ZnO), 43.59% (Ag₂O), and 49.91% (CrO₂). For CF₃CN adsorption, CuO-GaNNT exhibits an adsorption energy of -0.399 eV and a distance of 2.584 Å, Ag₂O-GaNNT shows -0.746 eV and 2.120 Å, CrO₂-GaNNT displays -0.243 eV and 3.040 Å, while ZnO-GaNNT undergoes chemical adsorption with a higher energy of -2.478 eV and a shorter distance of 1.319 Å. The adsorption capacity follows the order ZnO-GaNNT > Ag₂O-GaNNT > CuO-GaNNT > CrO₂-GaNNT. Regarding recovery at room temperature, Ag₂O-GaNNT, CuO-GaNNT, and CrO₂-GaNNT demonstrate favorable desorption behavior, whereas ZnO-GaNNT exhibits slower recovery due to stronger chemical bonding. These computational findings highlight the potential of metal oxide-modified GaNNTs as advanced materials for real-time detection of C₄F₇N and mitigation of its decomposition product, CF₃CN, in GIS HV equipment monitoring.