In this study, a structurally well-designed PdO@WO 3 core–shell, p–n heterojunction architecture was fabricated using a facile hydrothermal method. Its material characterization was performed via X-ray diffractometry, X-ray photoelectron spectroscopy, electron scanning microscopy, and transmission electron microscopy analyses. Besides, the gas sensing properties of pure WO 3 , PdO–WO 3 , and PdO@WO 3 nanocomposites were investigated. By benefiting from the unique synergistic effect between catalytic sensing and p–n heterojunction structure, the PdO@WO 3 core–shell nanostructure showed considerably enhanced acetone sensing performance compared with the other structures; especially, its response toward 50 ppm acetone gas was up to 40, four times higher than that of the pure WO 3 sensor. Its response/recovery times were also significantly reduced and its optimal operating temperature decreased from 250 °C to 200 °C. Finally, the possible sensing mechanism for the proposed PdO@WO 3 core–shell, p–n heterojunction architecture is discussed here; the considerable enhancement in the acetone sensing capability could be attributed to its well-designed fabrication.
As hydrogen is widely used as a clean energy source, the hazards of its flammable and explosive properties are gradually emphasized. Therefore, it is imminent to develop a hydrogen sensor with high response, fast detection speed and low detection limit. In this paper, a PdO/WO 3 composite with fruit-leaf-like structure was synthesized by in-situ hydrothermal and self-assembly impregnation method, and its H 2 sensing performance was investigated. The results show that the self-assembled loading of PdO can greatly improve the H 2 sensing performance of WO 3 , in which the PdO/WO 3 -1 sensor exhibits a very high response value (338.7) and a very short response/recovery time (1 s/4 s) at 120°C to 100 ppm H 2 . The enhanced sensor performance is mainly due to the catalytic effect of the noble metal PdO on H 2 and the synergistic effect between WO 3 and PdO. The growth rhythm of PdO nanoparticles and the effect on the H 2 sensing performance of PdO/WO 3 composites were also explained by varying the concentration of PdCl 2 solution. The density functional theory calculation proves that the hydrogen sensing performance is improved after the combination of PdO and WO 3 . This study provides a feasible solution for the development of high-performance WO 3 -based H 2 sensors.
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