Low palladium content CeO2/ZnO composite for acetone sensor with sub-second response prepared by ultrasonic method

In practical applications, noble metal doping is often used to prepare high performance gas sensors, but more noble metal doping will lead to higher preparation costs. In this study, CeO₂/ZnO-Pd with low palladium content was prepared by ultrasonic method with fast response and high selectivity for acetone sensing. With the same amount of palladium added, the selectivity coefficient of CeO₂/ZnO-Pd is 1.88 times higher than that of the stirred sensor. Compared with the pure PdO-doped CeO₂/ZnO-PdO material, the content of Pd in CeO₂/ZnO-PdO is about 30% of that in CeO₂/ZnO-PdO, but the selectivity coefficient for acetone is 2.56 times higher. The CeO₂/ZnO-Pd sensor has a higher response (22.54) to 50×10⁻⁶ acetone at 300 °C and the selectivity coefficient is 2.57 times that of the CeO₂/ZnO sensor. The sensor has a sub-second response time (0.6 s) and still has a 2.36 response to 330×10⁻⁹ of acetone. Ultrasonic doping makes Pd particles smaller and increases the contact area with gas. Meanwhile, the composition of n-p-n heterojunction and the synergistic effect of Pd/PdO improve the sensor performance. It shows that ultrasonic Pd doping provides a way to improve the utilization rate of doped metals and prepare highly selective gas sensors.