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Nanocomposites of SmFeO3/YFeO3 (1:0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, and 0:1) with different molar proportions were prepared by the sol–gel method. The material's properties were characterized by various test methods, such as scanning-electron microscopy (SEM) and X-ray photoelectron-diffraction spectrometry (XPS). The gas-sensing characteristics of the sensor were tested in darkness and under illumination using monochromatic light with various selected wavelengths. The test results show that the SmFeO3/YFeO3 sensor with the molar ratio of 0.4:0.6 had the highest gas response to volatile organic compound (VOC) gases and that the optimum operating temperature was lower (120 °C). The light illumination improved the sensor's sensitivity to gas. Under the 370-nanometer light illumination, the sensor's responses to 30 ppm of ethanol, acetone, and methanol gases were 163.59, 134.02, and 111.637, respectively, which were 1.35, 1.28, and 1.59 times higher, respectively, than those without light. The high gas sensitivity of the sensor was mainly due to the adsorption of oxygen on the material's surface and the formation of a p–p heterojunction. The SmFeO3/YFeO3 sensor, which can respond to different VOC gases, can be used to detect the safety of unknown environments and provide a timely warning of the presence of dangerous gases in working environments. [ABSTRACT FROM AUTHOR]

The planar electrode sensors of the La 1−x Y x FeO 3 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) perovskite material were prepared for volatile organic compounds (VOCs) gas detection. The La 1−x Y x FeO 3 (x = 0.8) sensor has a higher gas response than La 1−x Y x FeO 3 (x = 0, 0.2, 0.4, 0.6, and 1) due to a higher surface adsorbed-oxygen content of the material. Light illumination improves the gas response of the La 0.2 Y 0.8 FeO 3 sensor to VOCs gases. A higher gas response of the La 0.2 Y 0.8 FeO 3 sensor was attained as the light-source wavelength was shortened. The gas responses of the La 0.2 Y 0.8 FeO 3 sensor under 370 nm light illumination at 100 °C to 5 ppm ethanol, methanol, acetone, and formaldehyde were 36.369, 32.352, 36.357, and 12.545, respectively. Additionally, at 110 °C, the response to 5 ppm acetylacetone was 35.94. In conclusion, the La 0.2 Y 0.8 FeO 3 planar electrode sensor has greater gas responses and lower operating temperature to VOCs gases. Therefore, the planar electrode sensor can reduce power consumption and be used in various locations with known gases. • The La 1−x Y x FeO 3 gas sensors were prepared using 1.5 × 1 mm plane electrodes. • The La 0.2 Y 0.8 FeO 3 sensor has high responses to VOCs under light illumination. • The plane electrode sensor has a low optimum working temperature of 100 °C. • Multi-wavelength light illumination can improve the gas response of sensor. [ABSTRACT FROM AUTHOR]