Highly sensitive H₂ sensor based on PdO-decorated WO₃ nanospindle p-n heterostructure

A highly sensitive H-2 gas sensor based on n-WO3/p-PdO heterostructure has been fabricated. Using hydrothermal method, through tuning the pH value of the solution, WO3 nanospindles were synthesized. SEM reveals its uniform morphology; XRD result shows its high crystal quality; N-2 adsorption/desorption result proves its relatively high specific surface area. Through first soaking then calcinating method, PdO was loaded on the surface of WO3 nanospindles. XPS and HRTEM together have proved the fabrication of the heterostructure between n-WO3/p-PdO. The gas sensing device was fabricated by coating the PdO loaded WO3 paste on a ceramic substrate with silver palladium interdigital electrodes. After loaded into the test chamber, preheated to the required temperature and injecting a certain amount of H-2, the sensing procedure was done. With optimal ratio of loaded PdO to WO3 (3 at%), the sensor shows the best gas sensitivity at 150 degrees C. To 1, 5, 10, 20 and 50 ppm H-2, the sensor shows the response values (R-o/R-g) of 1.3, 7, 23, 37 and 76, in the response time of 9s, 8s, 5s, 3s and is, respectively. The quasi-one dimensional (QOD) character of WO3 nanospindle, the well-performance heterostructure between WO3 and PdO and the optimal ratio of loaded PdO to WO3 together make the sensor own strong sensing ability towards H-2. The such well-performance H-2 gas sensor based on n-WO3/pPdO heterostructure reminds us that the WO3/P-dO system has supplied a good material platform to explore the fabrication of ultrasensitive and stable H-2 gas sensor. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.