In this study, sea-urchin-like LaF3 doped mesoporous Co3O4 (La-Co3O4) nanomaterials were obtained by the heat treatment of citric acid-assisted hydrothermally-synthesized products at 300 °C. The composition, microstructure, and morphology were investigated by different characterization methods. Structural analyses reveal that La-Co3O4 has a hierarchical structure formed by the assembly of numerous nanorods that are aggregated by countless nanosheets. We probed the sensing ability of the La-Co3O4 based sensors toward a series of volatile organic gases, such as triethylamine, xylene, and ethanol. The results indicate that the sensors exhibited excellent selectivity and responsiveness toward triethylamine, with a lower detection limit of 1.0 ppm and long-term stability at an operating temperature of 195 °C. The prominent gas sensing performance first originates from the high content of adsorbed oxygen for doping LaF3 in which the high mobility of F anions resulted in the presence of F vacancies on the surface of the composites. Additionally, the abundant porosity offered by the hierarchical structure is favorable to the adsorption of oxygen species, surface reactions, and gas diffusion during the sensing process. Doping LaF3 to the semiconductor materials may provide a potential approach for the development of novel gas sensing materials.

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A mixed potential-type NO2 sensor was fabricated using yttria-stabilized zirconia (YSZ) as the electrolyte and mesoporous WO3 as the sensing electrode for the detection of NO2 in vehicle exhausts. The mesoporous WO3 with a diameter of 7 nm was synthesized using the hard template method. The sensor showed excellent performance in the detection of 30–500[Formula: see text]ppm of NO2 at 300∘C and 500∘C. However, commercial WO3 only operate well at 500∘C. The response of the mesoporous WO3 was higher and the test temperature was lower compared to that of commercial WO3. XPS combined with NO2-TPD was used to explain the high activity of mesoporous WO3 at medium-low temperature, and the mechanism of mixed electromotive force was verified by electrochemical impedance spectroscopy. Furthermore, the sensor exhibited high NO2 selectivity in the presence of interfering gases, such as NO, CO, CO2 and NH3. Most importantly, the sensor had excellent repeatability and stability.