PtPd NPs-functionalized metal–organic framework-derived α-Fe2O3 porous spindles for efficient low-temperature detection of triethylamine

In recent years, metal-organic framework (MOF) derivatives have gradually become ideal materials for gas sensors due to their controllable composition, diverse structures and open metal sites. In this research, a simplified hydrothermal method was applied to successfully prepare MOF-derived α-Fe₂O₃ spindles, and an in situ reduction method was then utilized to deposit Pt, Pd and PtPd bimetallic nanoparticles (NPs) on the α-Fe₂O₃ spindles. The effects of noble metals Pt, Pd and PtPd on the gas-sensing properties of Fe₂O₃ were systematically examined. The PtPd/α-Fe₂O₃ sensor has enhanced gas-sensing performance for triethylamine (TEA), especially at PtPd content of 1.5 wt% and mass ratio of Pt : Pd = 90 : 10, where the response of the sensor to 100 ppm TEA at a lower temperature of 150 °C is 442, which is 34 times higher than that of the original α-Fe₂O₃ (response of 13). Additionally, the sensor demonstrated improved response/recovery properties and very respectable selectivity, repeatability, long-term stability within 30 days and lower detection limit (500 ppb) at 150 °C. Combining the results of XPS and O₂-TPD, the enhanced gas-sensing properties of PtPd bimetallic-modified α-Fe₂O₃ over monometallic (Pt or Pd) modified α-Fe₂O₃ were analyzed, which can be attributed to the chemical and electronic sensitization of noble metals and the synergistic effect of the PtPd bimetallic NPs, resulting in more surface defects and enhanced oxygen adsorption capacity of the sensing material. This work provided an effective gas-sensing material for the low-temperature detection and analysis of triethylamine gas.