PdM双金属纳米晶的可控合成及其对金属氧化物气敏材料的多重增敏机理

近年来，智能手机、智能家居和可穿戴设备等消费类电子产品对微型化气体传感器的需求急速增加。但是目前的半导体气体传感器尺寸较大，工作温度较高、选择性和灵敏度不足，难以满足消费类产品的市场需求。. 尽管贵金属Pt和Pd的修饰提高了半导体气体传感器的敏感性能，但是由于没有化学和电子等增敏效应的协同，以及对增敏剂缺乏合理的设计，未能做到选择性和灵敏度的协同增强。 本课题拟通过对PdM双金属纳米晶生长的热力学和动力学调控，可控合成形貌、尺寸和暴露晶面可控的PdM双金属纳米晶，利用双组分与精细结构的协同效应增强敏感材料表面的气体吸附、反应和空间电荷层调控，实现化学、电子、异质结和微结构等多效增敏，满足消费类气体传感器的灵敏度与选择性可控以及微型化和低功耗的需求。通过原位表征技术和理论（第一性原理和分子动力学）计算相结合的方法揭示双金属纳米晶的多效增敏机理，为今后的气敏材料设计提供支持。

With the increasing demand in the areas of environmental monitoring and public security, an uncommon opportunity has been appeared for application of mini metal oxide semiconductor (MOS) gas sensors in smart phone, home and wearable devices. But current MOS gas sensors still have some disadvantages, such as higher working temperature and unsatisfactory sensitivity and selectivity, unclear gas sensing mechanism for understanding and shortage of rational design. It is difficult to meet the challenges of market request of consumer electronics, such as high sensitivity and selectivity, mini volume, low power and intelligent. So we have to reduce the size of sensor and design perfect sensing material, especially in sensitizer, to satisfy the market demand. . Although loading of Pt or Pd onto metal oxide gas sensing materials has beem proved to be a suitable route to improve gas sensing performance, gas selectivity and sensitivity could not be enhanced synergistically, owing to shortage of rational design and understanding of sensitizing mechanism of noble metal sensitizers. .We plan to design and prepare PdM bimetal nanocrystals with controllable morphology, size, and exposed crystal facet by combination with the methods of theory computation and experimental characterization. Through synergistic effect of chemical composition and microstructure of PdM bimetal nanocrystal to enhance the adsorption and reaction of oxygen and detecting gas on the surface of gas sensing material, we can further tune the thickness (Debye length, LD) of space charge layer and multi-effect enhance gas sensing by chemical sensitizing, electronic sensitizing, heterojunction and microstructure promotion. Thus we can achieve controllable .gas sensitivity and selectivity and low power mini devices to meet the demand of consumer gas sensors. Based on in-situ characterization (such as X-ray diffraction and adsorption, infrared spectroscopy, Laman spectroscopy, X-ray photoelectronics spectrum, gas chromatograph mass spectrometer and transient resistance measurement) and theory computation from the first principles and molecular dynamics simulation, we want to reveal the mechanism of enhancing effect with multiple-effect of bimetal nanocrystals, and present a support of theory method and experiment for design of gas sensing materials, especially in sensitizer.