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

A highly sensitive H 2 gas sensor based on n-WO 3 /p-PdO heterostructure has been fabricated. Using hydrothermal method, through tuning the pH value of the solution, WO 3 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 WO 3 nanospindles. XPS and HRTEM together have proved the fabrication of the heterostructure between n-WO 3 /p-PdO. The gas sensing device was fabricated by coating the PdO loaded WO 3 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 WO 3 (3 at%), the sensor shows the best gas sensitivity at 150 °C. To 1, 5, 10, 20 and 50 ppm H 2 , the sensor shows the response values (R a /R g) of 1.3, 7, 23, 37 and 76, in the response time of 9s, 8s, 5s, 3s and 1s, respectively. The quasi-one dimensional (QOD) character of WO 3 nanospindle, the well-performance heterostructure between WO 3 and PdO and the optimal ratio of loaded PdO to WO 3 together make the sensor own strong sensing ability towards H 2. The such well-performance H 2 gas sensor based on n-WO 3 /p-PdO heterostructure reminds us that the WO 3 /PdO system has supplied a good material platform to explore the fabrication of ultrasensitive and stable H 2 gas sensor. Image 1 • Quasi-1D WO 3 nanospindles were synthesized by facile hydrothermal method. • P-type PdO with strong catalytic ability to H 2 was loaded on n-type WO 3 nanospindles. • The sensor based on n-WO 3 /p-PdO heterostructure was fabricated. • Towards H 2 , the detection limit of the sensor is 1 ppm, within 9 s. • The H 2 gas sensor shows good stability. [ABSTRACT FROM AUTHOR]