Effects of Chemical State of the Pd Species on H(2) Sensing Characteristics of PdO(x)/SnO(2) Based Chemiresistive Sensors

In this paper, the PdO(x) nanoparticles modified SnO(2) are prepared using sputtering and wet chemical methods. The SnO(2) nanoparticles are separately added to a concentration of 0.75% to 10% PdCl(2) to obtain a PdCl(2)/SnO(2) composite material, which is calcined for 1 to 2 h at the temperatures of 120 °C, 250 °C, 450 °C and 600 °C. The PdO(x)/SnO(2) nanocomposite was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Microstructural observations revealed PdO(x) with different chemical states attached to the surface of SnO(2). Hydrogen response change tests were performed on the obtained PdO(x)/SnO(2) gas sensing materials. The results show that the high gas sensing performance may be attributed to the contribution of the PdO(x)-loaded SnO(2). In hydrogen, the best sensitivity response was attained at 80 °C, which is 60 times that of pristine SnO(2). It clarifies the role of PdO(x) in the gas sensing mechanisms.