A high sensitivity gas sensor for formaldehyde based on silver doped lanthanum ferrite

The gas-sensing properties of silver doped lanthanum ferrite (Ag–LaFeO3) compounds for formaldehyde were investigated in this paper. Ag–LaFeO3 powders were prepared using sol–gel method combined with microwave chemical synthesis. The powders were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The formaldehyde gas-sensing characteristics for the sample were examined between 65 °C and 220 °C. The experimental results indicate that the sensor based on the sample Ag–LaFeO3 shows excellent gas-sensing properties to formaldehyde gas and the operating temperature is very low. At the optimal operating temperature of 90 °C, the response of the sensor based on Ag–LaFeO3 to 1 ppm formaldehyde is 25, while to other test gases, the response is all lower than 6. With increasing concentration of formaldehyde, the resistance of the sensor based on the sample Ag–LaFeO3 increases. The response and recovery times for the sample to formaldehyde gas are 65 s and 60 s, respectively.