Synthesis,characterization and formaldehyde gas sensitivity of La0.7Sr0.3FeO3 nanoparticles assembled nanowires

La_0.7Sr_0.3FeO₃ nanoparticles assembled nanowires were synthesized by a hydrothermal method assisted with cetyltrimethylammonium bromide (CTAB). The hydrothermal temperature was 180 °C and the annealed temperature was 700 °C. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphology, composition and structural properties of the materials. The results showed that the La_0.7Sr_0.3FeO₃ nanoparticles assembled nanowires had a high aspect ratio (the largest aspect ratio >100); the size of the nanoparticles was about 20 nm and the diameter of the nanowires was about 100–150 nm. The growth mechanism of La_0.7Sr_0.3FeO₃ nanowires was discussed. Gas sensors were fabricated by using La_0.7Sr_0.3FeO₃ nanowires. Formaldehyde gas sensing properties were carried out in the concentration range of 0.1–100 ppm at the optimum operating temperature of 280 °C. The response and recovery times to 20 ppm formaldehyde of the sensor were 110 s and 50 s, respectively. The gas sensing mechanism of La_0.7Sr_0.3FeO₃ nanowires was investigated.