Advancing Understanding of Semiconducting Oxide Nano-Heterostructure Gas Sensors

非技术描述：该项目通过加速选择性、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。这项工作的目的是通过对传感机制的基本理解来破坏气体传感器中试错材料发现的周期，从而使纳米材料的自下而上设计和工程能够用于特定应用。从这项研究中获得的知识为寻求以下领域提供了重要贡献：（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的环境破坏;（2）实现食品新鲜度的实时自动监测，以减少食品浪费并有助于可持续性，以及（3）便于部署能够快速筛查呼出气中与一系列健康状况和癌症相关的生物标志物的便携式传感器，帮助难以获得先进医疗保健技术的人群尽早发现疾病。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，该社区越来越多地在日本，韩国，中国和欧洲的几个团体的国际努力中发挥领导作用。具体而言，他们将成为纳米材料电学测量和通过电子显微镜进行最先进的电子特性表征的专家。技术规格：最近纳米材料研究的激增已经开发了许多将半导体氧化物合成为纳米结构的新方法，特别是将材料组合成单一结构，称为纳米异质结构。然而，对新合成方法的关注导致了对用于气体传感器应用的材料发现的主要试错方法，而对潜在机制的基本理解很少。这项研究的主要重点是开发和发布一个全面和统一的模型，用于气体与纳米异质结构的相互作用，该模型将提供一个框架，使该领域的其他人能够更有效地设计新结构，并最终加速其在设备中的实现。该项目旨在从经过验证的纳米异质结构传感器材料中获得基础知识，方法是：（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特性;（二）利用对单个纳米线和纳米线簇的电测量来将界面的贡献与体相分离，氧化物成分作为环境条件的函数;和（3）建立真正代表纳米材料的气体-氧化物和氧化物-氧化物界面处的电子相互作用的模型，而不是基于体理想性质。此外，正在建立一个开放式在线数据库，收集连续型气体传感器的已发表结果，以帮助该领域的研究人员确定材料特性的趋势和传播重要结果，并帮助工业界确定最有前途的技术用于特定应用。

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.