Issues like morphology control and further multifunctional applications are of significant importance for rare earth nano-oxides, e.g., cerium dioxide (CeO2) nanostructures, however, relevant results in this respect are rather limited up to now. In the present work, ultrathin CeO2 nanosheets were synthesized through a facile low-temperature hydrothermal method. The structure, morphology and specific surface area of these CeO2 nanosheets were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and N2 adsorption–desorption. Significantly, CeO2 nanosheets have the potential as bifunctional sensing materials to detect both humidity and formaldehyde vapor. The CeO2 nanosheet humidity sensor exhibited excellent sensing characteristics in the relative humidity range of 11%–97% with the response value as high as 3.1 × 104. Meanwhile, the CeO2 nanosheet gas sensor showed superior sensitivity and repeatability with fast response/recovery speed toward formaldehyde vapor at 300 °C. Finally, the humidity and formaldehyde sensing mechanism were discussed as well.

中文翻译：

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超薄 CeO2 纳米片作为双功能传感材料用于湿度和甲醛检测

形貌控制和进一步的多功能应用等问题对于稀土纳米氧化物，例如二氧化铈 (CeO2) 纳米结构具有重要意义，然而，到目前为止，这方面的相关结果相当有限。在目前的工作中，超薄 CeO2 纳米片是通过一种简便的低温水热法合成的。通过X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）和N2吸附-解吸对这些CeO2纳米片的结构、形貌和比表面积进行了表征。值得注意的是，CeO2 纳米片具有作为双功能传感材料检测湿度和甲醛蒸汽的潜力。CeO2纳米片湿度传感器在11%~97%的相对湿度范围内表现出优异的传感特性，响应值高达3。1 × 104。同时，CeO2 纳米片气体传感器表现出优异的灵敏度和可重复性，在 300 °C 时对甲醛蒸汽具有快速响应/恢复速度。最后，还讨论了湿度和甲醛的传感机制。