Utilizing Synergistic Effect in Pd-Doped Mesoporous γ-Al2O3/SnO2 for Multiple Freon Refrigerant Gases Detection

Abstract

Freon refrigerants, whose leakage will cause serious safety and environmental issues, have an urgent need of developing leakage detection technologies. Conventional metal oxide semiconductor (MOS) gas sensors exhibit limited efficacy in detecting halogenated Freons due to their chemical inertness and weak charge-transfer interactions. While recent innovations employing mesoporous γ-Al₂O₃ overlayers have enabled Freon detection via catalytic decomposition sensing mechanism, the achieved sensing performance remains suboptimal. In this work, this issue is addressed by engineering a Pd-doped mesoporous γ-Al₂O₃/SnO₂ (Pd-γ-Al₂O₃/SnO₂) gas sensor. The doped Pd atoms not only accelerate the decomposition of Freon molecules on the catalytic layer but also induce the Schottky-barrier effect in the SnO₂ sensing layer. Benefiting from the synergistic effect, the Pd-γ-Al₂O₃/SnO₂ gas sensor shows outstanding response, good stability, repeatability, selectivity, and rarely-reported universality in sensing different Freon gases. Notably, a valuable solution is demonstrated in the leakage detection of next-generation refrigerants, Freon R1234yf. The sensing mechanism is deduced by exhaust gas components identification. These results highlight the promising potential for addressing the real-world needs of Freon refrigerant leakage detection technology.