Probing the dynamic evolution of active species under different sensing conditions is achieved to the rational design of sensing materials for outstanding sensing performance. In this study, a palladium (Pd)-loaded ZnO sensing material was approached via the impregnation method. The Pd-loaded ZnO100 gas sensor has a better H2 sensing performance than a pure ZnO gas sensor at an operating temperature of 190 to 360 °C. The in situ Raman and H2 temperature-programmed surface reaction characterization technologies confirmed that the synergistic effect of metal Pd (Pd0) and Pd oxide (PdOx) played a decisive role in improving the sensing capability for H2 in low concentrations (less than 100 ppm). The proportion of Pd0 in the Pd/PdOx dynamically increased with the elevation of operating temperature. The small size Pd/PdOx dispersed on the ZnO surface enhanced the dissociation of H2 by Pd0 and the charge transfer between PdOx and ZnO, boosting the sensing performance of the gas sensor to H2. With the increase of the operating temperature to more than 360 °C, H2 was directly oxidized to gaseous H2O on the Pd/PdOx active sites, resulting in a relatively low H2 sensing capacity. In addition, the change of the appropriate Pd/PdOx ratio could effectively improve the H2 sensing performance of the gas sensor.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Renewable Energy, Sustainability and the Environment