Ratiometric Fluorescent Probe with Metal-Mediated Dual-Emission Centers for Ultrasensitive and Interference-Resistant SF ₆ Monitoring in High-Voltage Equipment

Developing SF₆ detection method with convenient, efficient, and interference-resistant is crucial for monitoring gas leaks in grid insulation systems. Here, we report a novel ratiometric fluorescent probe (NiCDs@MOF) with dual-emission centers, where carbon dots (NiCDs) are anchored within a Ni-based MOF via a Ni-bridge coordination. This designed probe could efficiently recognize and capture SF₆ molecules via multisite interactions between the fluorophilic sites on NiCDs and naphthalene ligands within luminescent-MOF (LMOF) pores. This adsorption triggered an interfacial charge transfer, leading to distinct and opposite changes in the dual-fluorescence intensities. Based on this ratiometric response, the developed probe enabled highly sensitive and selective detection of SF₆, achieving an ultralow detection limit of 2.8 ppb within 3 min and exhibiting excellent anti-interference capability against five common interfering gases. Furthermore, its ratiometric signal output ensured outstanding performance with excellent reusability (RSD < 2.7% over 5 cycles) and high photostability (fluorescence fluctuation <5% under continuous irradiation for 3600 s), offering a robust and innovative approach for SF₆ leakage monitoring.