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Urchin-like WO2.72 microspheres modified with Au and PdO nanoparticles were constructed and applied to the field of gas sensors. The gas-sensing test results showed that the Au/PdO/WO2.72 sensors exhibited excellent gas-sensitive performances. The sensors have not only an ultrahigh response to TMA but also a rapid response/recovery time. Especially WO2.72 decorated with 2 wt % Au and 2 wt % PdO nanoparticles (2%AuPW), its response to 40 ppm of TMA can be up to 802.5 at 240 °C, which is approximately 110.5 and 1.6 times of WO2.72 (7.26) and 2 wt % PdO/WO2.72 (496.6) at 260 °C, respectively. Even for 1 ppm of TMA, the response of the as-obtained 2%AuPW sensor can still attain 10.9. Furthermore, the Au/PdO/WO2.72 sensor showed excellent effectiveness after 30 days. The BET results indicate that the deposition of PdO and Au nanoparticles increases the specific surface area of the sample. The mechanism analysis revealed that the markedly increased gas-sensing properties of Au/PdO/WO2.72 sensors are ascribed to the synergy of surface area and a mesoporous structure, a p–n heterojunction, and a catalytic spillover effect of PdO and Au nanoparticles. The rational design and detailed investigation of Au/PdO/WO2.72 sensors provide insights into the development and design of other semiconductor-based sensors.

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