Ordered mesoporous Pd/SnO 2 synthesized by a nanocasting route for high hydrogen sensing performance

Abstract

Ordered mesoporous SnO 2 and mesoporous Pd/SnO 2 have been successfully synthesized via nanocasting method using the hexagonal mesoporous SBA-15 as template. Two different procedures, impregnation technique and direct synthesis, were utilized for the doping of Pd in the mesoporous SnO 2. The results of small angle X-ray diffraction (SAXD), nitrogen adsorption–desorption and transmission electron microscopy (TEM) demonstrate that the SnO 2 and Pd/SnO 2 display ordered mesoporous structures and high surface areas. Wide angle X-ray diffraction (WAXD) and X-ray photoelectron spectroscopy (XPS) reveal tetragonal structure of SnO 2 and the existence of Pd element. The sensing properties of mesoporous SnO 2 and mesoporous Pd/SnO 2 for H 2 were detected. The sensor utilizing mesoporous Pd/SnO 2 via direct synthesis method exhibits excellent response and recovery behavior and much higher sensitivity to H 2, compared to those using mesoporous SnO 2 and mesoporous Pd/SnO 2 via impregnation technique. It is believed that its high gas sensing performance is derived from the large surface area, high activity and well dispersion of Pd additive, as well as high porosity, which lead to highly effective surface interaction between the target gas molecules and the surface active sites.