WO₃ Nanosheets/FeCo₂O₄ Nanoparticles Heterostructures for Highly Sensitive and Selective Ammonia Sensors

The gas - sensitive properties of metal oxide nanocomposites mainly depend on their structure and composition. In this paper, a highly sensitive ammonia sensor based on FeCo2O4nanoparticles modified WO3nanosheet nanocomposite is prepared. The structure and composition of the sensor material are characterized by the systematic spectral and structural characterization. The results show that FeCo2O4nanoparticles grow on the surface of WO3nanosheet and the interfacial contact is close, which leads to the P-N heterojunction and the increase of the relative specific surface area. The gas sensitivity test results show that the WO3/FeCo2O4gas sensor has the highest sensitivity to NH3(33.5 at 100 ppm) at 300 °C, with the characteristics of satisfactory selectivity, short response/recovery time, high repeatability and long stability. Compared with the intrinsic properties of WO3and FeCo2O4, the sensitivity of WO3/FeCo2O4nanocomposites is improved by tens of times. These excellent properties are attributed to the P-N heterojunction between WO3nanosheets and FeCo2O4nanoparticles, as well as the good catalytic activity of FeCo2O4, which make it become a practical gas sensitive material for ammonia detection.