Sensitization of Pd loading for remarkably enhanced hydrogen sensing performance of 3DOM WO3

Three-dimensionally ordered macroporous (3DOM) WO3 materials were synthesized via colloidal crystal template method. Pd loading, aimed to improve the sensing performance of the sensor to hydrogen, was carried out by reducing Pd (II) centers. The obtained Pd-loaded 3DOM WO3 samples were carefully characterized by XRD, Raman, SEM, TEM, XPS, UV-vis, Hall and the gas sensing properties targeting ppm level hydrogen were examined. The response of the Pd-loaded 3DOM WO3 to 50 ppm H-2 is up to 382 at a low working temperature of 130 degrees C, which is approximately 225 times higher than that of the pure 3DOM WO3. Additionally, the sensor displays fast response (10s) and recovery (50s). More importantly, the Pd-loaded 3DOM WO3 shows superior response to hydrogen with negligible response towards other interfering gases, indicating that the sensor exhibits excellent selectivity to hydrogen. Furthermore, the possible gas sensing mechanism based on the model of depletion layer is proposed to demonstrate that, both the structural defects and the sensitization exerted by Pd are responsible for the outstanding performance in hydrogen sensing. (C) 2018 Elsevier B.V. All rights reserved.