Enhanced sensitivity to toluene gas based on polyoxometalate electron acceptor-decorated CeO2 composite gas sensor

As a classical rare earth oxide, cerium dioxide (CeO 2 ) has played an important role in the realm of gas detection. Nonetheless, pure CeO 2 as a gas sensor material is challenged by a wide band gap, rapid carrier recombination, and high operating temperature, which affects its efficacy. Constructing heterogeneous composite materials is an effective method to remedy this issue. Herein, we introduced polyoxometalate (POMs, cluster formations of rare metal oxides.) electron acceptor into CeO 2 gas sensor for the first time to investigate the effect of POMs on gas sensitive properties. As a result, the CeO 2 /PW 12 gas sensor responds quickly and recovers promptly, showing a value of 8.41 to 100 ppm of toluene gas, which is much higher compared to pure CeO 2 sensor (3.05). And then CeO 2 /PW 12 sensor response recovery time of 6 s/71 s. Selectivity, repeatability, long-term stability and humidity resistance were also comprehensively explored. The results show that the sensor has the highest response value at 1 % PW 12 content. And the sensor showed good long-term stability and humidity resistance. The sensor has a minimum detection limit of 77.434 ppb for toluene. The improved sensing capabilities are a result of the incorporation of PW 12 . It serves as a shallow electron trap, capturing electrons within the conduction band of CeO 2 , thus the electron-hole pairs could be effectively separated. In that way the gas sensing performances of CeO 2 sensor were successfully improved. The research presented in this article outlines a novel approach to creating highly sensitive gas sensors utilizing CeO 2 , offering valuable insights into the utility of polyoxometalates in gas detection applications.