Humidity-tolerant and highly sensitive gas sensor for hydrogen sulfide based on WO₃ nanocubes modified with CeO₂

The influence of ambient humidity on the gas-sensing characteristics of metal oxide semiconductors has been one of the greatest obstacles for gas-sensing applications. In this paper, the pure WO₃ and CeO₂-modified WO₃ nanocubes were prepared by a simple hydrothermal method, and their gas-sensing characteristics in dry and humid atmospheres were investigated. The results show that CeO₂/WO₃ demonstrated excellent gas-sensing properties toward H₂S with high sensitivity and high selectivity at 115 °C. Noteworthy, the humidity independence of the CeO₂/WO₃ increased compared to the WO₃. The response retentions over the whole humidity range of the CeO₂/WO₃-6 and CeO₂/WO₃-15 sensors were 70.3, and 76%, respectively, which were much higher than the WO₃ sensor (17.9%). The gas-sensing mechanism of CeO₂-modified WO₃ is discussed based on the gas sensitivity properties. The obtained results provide a promising route to enhance the anti-humidity properties of metal oxide semiconductor gas sensors.