Sensors based on porous Pd-doped hematite (α-Fe₂O ₃) for LPG detection

In this work, sensors based on nanoparticles of α-Fe ₂O₃ doped with different amounts of Pd ranging from 0.1 to 1.0 wt.% were prepared by coprecipitation for liquefied petroleum gas (LPG) detection. Solids were characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), adsorption-desorption of N₂ (BET surface), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Sample tests of Pd-doped sensors showed much higher sensitivity than the undoped one revealing the promotion electronic effect of Pd²⁺ on the surface reaction. Among all samples, the sensor with 0.75 wt.% Pd presented the highest gas response at 300 C in all gas tested concentrations, likely due to the highest BET surface, well-defined hematite crystalline structure and best surface contact over Pd surface via electronic mechanism.