分级多孔结构NiO/ZnO复合材料制备及其甲醛气敏性能

以向日葵秸秆为生物模板合成一种新型的分级多孔结构氧化镍掺杂氧化锌纳米复合材料(Bio NiO/ZnO),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)对复合材料的组成和结构进行表征.实验结果表明，合成的Bio NiO/ZnO保存了向日葵秸秆材料的原始分级多孔结构，该结构由大量尺寸和形状一致的六方晶系纤锌矿型结构的氧化镍与立方晶系文石相结构的氧化镍球形颗粒堆积组成.与未掺杂的ZnO材料相比，Bio NiO/ZnO复合材料制作的气敏传感器对甲醛具有增强的气敏性能.在240℃的工作温度下，该气体传感器对10^-4的甲醛的响应为42,响应和恢复时间分别为7 s和6 s.检测的下限为1.48×10^-4,与复合物的氧空位浓度增加和两相间p-n型异质结的存在有关.

Preparation of Graded Porous NiO/ZnO Composites and Their Formaldehyde Gas-Sensitive Properties

Sunflower straw was used as a biological template, a novel graded porous structure of nickel oxide doped zinc oxidenanocomposite (Bio NiO/ZnO) was synthesised.  The composition and structure of the composite were characterised by using X-ray diffraction (XRD),  scanning electron microscopy (SEM),  transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results show that the synthesised Bio NiO/ZnO preserves the original graded porous structure of the sunflower straw material,  which consists of a large number of hexagonal crystalline fibrillated ZnO-type structures of uniform size and shape stacked with spherical particles of nickel oxide in a cubic crystalline aragonal phase structure.  Compared with the undoped ZnO material,   a gas sensor made of Bio NiO/ZnO composite  material has enhanced gas sensitivity to formaldehyde.  The response of the gas sensor to formaldehyde of 10^-4   is 42 at an operating temperature of 240 ℃， the response time and recovery time are 7 s and 6 s respectively. The lower limit of detection is 1.48×10^-4, which is  related to the increased concentration of oxygen vacancies in the complex and the existence  of p-n type heterojunctions between the two phases.