Batch fabrication of H2S sensors based on evaporated Pd/WO3 film with ppb-level detection limit

H2S is an extremely toxic gas that can cause damage to the respiratory and nervous systems or even death, therefore it is of great significance to develop high performance H2S sensors. However, traditional techniques including brush painting and drop casting methods adversely affect the batch response consistency of the sensors owing to the uncontrollable film formation process, impeding the mass industrial manufacture of gas sensors. In this work, WO3 and Pd are sequentially deposited onto alumina substrates by e-beam evaporation. The results show that the Pd/WO3 sensor exhibits high sensitivity (2.68 ppm- 1), short response time (14 s toward 0.7 ppm), and low detection limit (50 ppb) toward H2S at an optimal operating temperature of 250 degrees C. Moreover, owing to the uniform distribution of Pd/WO3 film, the prepared H2S sensors present a good batch response uniformity with a low relative standard deviation of response values of less than 4.80%. This work provides an effective method for batch-preparing high performance H2S sensors with ppb-level detection limits, which is expected to realize a reliable and massive fabrication method for gas sensors.