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

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.

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。

近年来，物联网的快速发展和消费类智能产品对半导体气体传感器低功耗、低成本、微型化和多功能化等方面的要求更加迫切。但是，由于目前的气体传感器尺寸较大，功耗和工作温度偏高，气敏性能还不能满足这些新兴领域的技术要求。因此，加深对贵金属敏化剂增敏机理以及金属氧化物半导体气敏机理的理解，通过不同化学组分与微观结构的协同增强（化学、电子、异质结与微结构协同增敏等），在新型微纳平台（如微热片）上研发小型化、低功耗、高响应和良好选择性的高性能气体传感器，有利于满足消费类电子产品对气体传感器的市场需求，在保障人身安全和公共安全方面也具有重要的应用价值。.本课题主要研究内容及其取得的重要成果如下：.1、采用晶种生长法可控合成了暴露晶面可控的Pd纳米晶；采用水热还原法等合成了Au、Pt纳米颗粒， PdIr三维多孔纳米颗粒，PdNi、PdAu和PdPt纳米晶，IrNi纳米晶，PdRh合金框架和Pd@Au核壳纳米粒子等增敏材料，为双金属纳米晶增敏性能和多重增敏机理的研究提供了物质基础。.2、发现了双金属纳米晶对氧化物半导体气敏材料的协同增敏效应以及发现了晶面依赖的的气敏性能，阐明了双金属纳米晶的增敏机理；提出了一种基于双金属纳米晶的双选择性多功能气体传感器材料设计策略，验证了双金属纳米晶在高性能、低功耗、多功能的气体传感器设计和制备中应用的可能性。如PdPt/SnO2可在低温检测CO，高温检测CH4气体,PdAu/SnO2可在低温检测甲醛，高温检测丙酮。.3、发现了晶面依赖的氧化锌气敏性能，理论和实验相结合揭示了氧空位及其锌间隙离子等施主缺陷对氧化锌的增敏机理；在此基础上，通过材料设计有意引入氧空位和锌间隙离子缺陷，增强了氧化锌纳米片的酒敏性能。.截止2021年1月，受本项目资助发表的SCI论文为27篇，中文核心期刊5篇；国际会议邀请报告6次，主旨报告2次，口头报告4次，墙报展示8次；全国学术会议特邀报告8次，邀请报告3次；申请发明专利7项，实用新型专利1项，授权发明专利3项，授权实用新型专利1项。培养博士研究生4名，硕士研究生12名。