Advancing Understanding of Semiconducting Oxide Nano-Heterostructure Gas Sensors

非技术描述：该项目加速了选择性、低功耗便携式气体传感器的开发，为社会带来了直接的技术效益。这项工作的目的是打破气体传感器中试错材料发现的循环，通过发展对传感机制的基本了解，使自下而上的纳米材料设计和工程能够面向特定应用。从这项研究中获得的知识为该领域寻求：(1)加强对有毒或易燃气体泄漏的快速检测，否则可能造成大规模环境破坏；(2)实现对食品新鲜度的实时自动监测，以减少食品浪费，帮助实现可持续性；以及(3)促进便携式传感器的部署，这些传感器能够快速筛查呼气中与一系列健康状况和癌症相关的生物标志物，帮助难以获得先进医疗保健技术的人群进行早期检测。由该项目资助的两名研究生正在发展成为美国传感器社区的未来领导者，该社区正日益屈服于日本、韩国、中国和欧洲几个组织的国际努力。具体地说，他们将成为通过电子显微镜进行纳米材料电学测量和最先进的电子性能表征的专家。技术细节：最近纳米材料研究的浪潮发展了许多新的方法来将半导体氧化物合成成纳米结构，特别是将材料组合成单一结构，称为纳米异质结构。然而，对新的合成方法的关注导致了对气体传感器应用中的材料发现的主要是反复试验的方法，对潜在的机理几乎没有基本的了解。这项研究的主要重点是开发和发布一个全面和统一的气体与纳米异质结构相互作用的模型，该模型将提供一个框架，使该领域的其他人员能够更有效地设计新结构，并最终加快它们在设备中的实施。该项目通过以下方式寻求已被证实为纳米异质结构的传感器材料的基础知识：(1)使用最先进的高分辨率电子显微镜技术，以单个纳米颗粒为基础评估这些材料的电子结构和性质；(2)利用对单根纳米线和纳米线簇的电学测量，将界面和块体的贡献分开，并绘制每种氧化物成分随环境条件的函数图；以及(3)建立真正代表纳米材料的气体-氧化物和氧化物-氧化物界面的电子相互作用的模型，而不是基于块体的理想性能。此外，正在建立一个开放访问的在线数据库，其中包括已发表的阻性气体传感器成果，以帮助该领域的研究人员确定材料性能的趋势和传播重要成果，以及帮助行业确定特定应用的最有前途的技术。

NON-TECHNICAL DESCRIPTION: This project has direct technological benefits to society by enabling the accelerated development of selective, low-power portable gas sensors. This work is purposely structured to disrupt the cycle of trial-and-error materials discovery in gas sensors by developing a fundamental understanding of the sensing mechanisms to enable bottom-up design and engineering of nanomaterials toward specific applications. The knowledge gained from this research provides crucial contributions to the field seeking to: (1) enhance rapid detection of leaks of toxic or flammable gases that could otherwise cause massive environmental damage; (2) enable real-time automated monitoring of food freshness to reduce food waste and aid sustainability, and (3) facilitate deployment of portable sensors capable of rapid screening for biomarkers in exhaled breath that correlate with a range of health conditions and cancers, aiding early detection efforts in populations lacking easy access to advanced health care technology. The two graduate students funded by this project are being developed into future leaders in a U.S. sensor community that is increasingly yielding leadership to international efforts in Japan, South Korea, China, and several groups in Europe. Specifically, they will become experts in nanomaterial electrical measurements and state-of-the-art electronic properties characterization via electron microscopy. TECHNICAL DETAILS: A recent surge in nanomaterials research has developed many novel methods for synthesizing semiconducting oxides into nanostructures, especially with combinations of materials into a single structure, termed a nano-heterostructure. However, the focus on new synthesis methods has led to a largely trial-and-error approach toward materials discovery for gas sensor applications with little fundamental understanding of the underlying mechanisms. The primary focus of this research is to develop and publish a comprehensive and unifying model for interactions of gases with nano-heterostructures that will provide a framework which enables the rest of the field to more effectively design new structures and ultimately accelerate their implementation into devices. This project seeks fundamental knowledge from proven sensor materials engineered into nano-heterostructures by (1) using state-of-the-art high-resolution electron microscopy techniques to evaluate the electronic structure and properties of these materials on an individual nanoparticle basis; (2) utilizing electrical measurements on single nanowires and clusters of nanowires to separate contributions of interfaces from the bulk and mapping the effects of each oxide constituent as a function of environmental conditions; and (3) building a model of the electronic interactions at the gas-oxide and oxide-oxide interfaces truly representative of nanomaterials and not based on bulk ideal properties. Additionally, an open-access on-line database is being constructed of resistive-type gas sensor published results to aid researchers in the field in identifying trends in materials properties and disseminating important results, as well as helping industries to identify the most promising technologies for a specific application.