Pd nanoparticles composited SnO2 microspheres as sensing materials for gas sensors with enhanced hydrogen response performances

Abstract

Abstract SnO 2 -composite Pd nanoparticles (0, 2.5, 7.5, 10 mol% Pd loading) were synthesized via solvothermal method, followed by calcination. The structure, morphology, chemical state and specific surface area of the Pd-SnO 2 composite were analyzed with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N 2 physisorption, respectively. It is found that the composites consist of large amount of SnO 2 microspheres with average diameters up to hundreds of nanometers, and the microspheres are assembled by numerous nanoparticles with average sizes of about 8 nm. To demonstrate their potential application, gas sensors based on the as-synthesized Pd-SnO 2 composites were fabricated to test their sensing performances. The 10 mol% Pd-SnO 2 composite shows an excellent sensing response towards different concentrations of hydrogen at 200 °C. The highest sensing response is up to 315.34 for 3000 ppm hydrogen with a fast response-recovery time (4 s/10 s), which is over 8 times higher than that of pristine SnO 2 , and the lowest detection limit is down to 10 ppm. More significantly, it presents excellent selectivity and stability for hydrogen. The improved sensing response characteristics of the composite could be attributed to the chemical sensitization and electronic sensitization of Pd catalyst.