Excellence in Research: Investigation of Small Molecule Adsorption and Conversion on the Semiconductor/Ionic-Liquid Interface and Application to Sensing and Catalysis

小气体分子的检测在工业、环境和其他应用中非常重要。开发能够以更高的灵敏度和选择性测量关键气体水平的传感器对于在某些情况下减少这些气体的量的努力非常重要。灵敏度是指能够测量非常少量的气体，选择性是指当存在许多其他气体时能够检测到特定的气体。该项目由综合活动办公室（OIA）和化学部门的化学结构动力学和机制（CSDM-A）项目资助。Wang， Riley和Sunda-Meya正在使用电化学，计算和显微镜方法开发基于离子液体的新型传感器，可以以非常高的灵敏度和选择性测量气体水平。离子液体是一种室温液体，它含有离子（带电分子）而不是中性分子。正在开发的传感器适合非常小的设备，可以在许多不同的地方和应用中使用。除了传感器的发展，研究将气体分子结合在一起的化学键强度的新方法也在设计之中。这项工作的广泛影响是多方面的，因为新开发的传感器可以帮助监测、改善和消除对人类和环境有害的气体。该项目的主要特点之一是本科生的直接参与，使他们有机会学习物理科学研究的许多方面，组织数据，准备/展示科学结果和结论。本项目包括理论和实验研究，旨在研究半导体/离子液体（SC/IL）界面的结构，这些界面上的有效选择性吸附，吸附对吸附剂结合强度的影响，以及其中涉及的分子机制的理解。这是一项基础研究，对未来任何涉及微型传感器、气体分离或利用ILs和/或SCs的高性能催化转化的项目都具有重要意义。这项系统的研究正在使用最先进的电化学、光谱、表面科学和计算化学方法进行。该项目的主要目标是对IL/SC界面上的小分子吸附有更深入的了解，并在这些界面上探索新的化学和物理。ILs生成非常独特的类实体界面；因此，它们可以产生极高的电场，并在固/液界面处诱导出异常大的电荷密度。双电层（EDL）电荷密度可以比传统的场效应高得多，并且可以实现新的静电调制水平。IL本身的纯离子结构也带来了静电环境，这可能被操纵以促进某些小分子的活化。然而，电气化的IL/电极界面，特别是SC的，吸附气体分子还没有理论或实验研究。本研究利用SC与IL界面可调性之间的强相互作用，通过系统研究IL环境下的吸附行为，实现和评价既敏感又选择性的气体吸附。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The detection of small gas molecules is extremely important in industrial, environmental, and other applications. Developing sensors that can measure levels of critical gases with greater sensitivity and selectivity is of great importance in efforts to reduce the amounts of these gases in certain situations. Sensitivity refers to being able to measure very small amounts of the gases and selectivity refers to being able to detect a particular gas when there are many other gases present. In this project funded by the Office of Integrative Activities (OIA)and the Chemical Structure Dynamics and Mechanisms (CSDM-A) program of the Chemistry Division, Drs. Wang, Riley, and Sunda-Meya are using electrochemical, computational, and microscopy methods to develop new sensors, based on ionic liquids, that can measure gas levels with very high sensitivity and selectivity. An ionic liquid is a room-temperature liquid that, instead of neutral molecules, contains ions (charged molecules). The sensors that are being developed to fit into very small devices and can be used in many different places and applications. In addition to the development of sensors, new methods for investigating the strengths of bonds that hold gas molecules together are being designed. The broader impacts of this work are many, as the newly developed sensors can aid in monitoring, ameliorating, and eliminating gases that are harmful to people and the environment. One of the key features of the project is the direct involvement of undergraduates, giving them opportunities to learn many aspects of research in the physical sciences, organization of data, and preparation/presentation of scientific results and conclusions.This project entails both theoretical and experimental studies aimed at investigating the structures of semiconductor/ionic liquid (SC/IL) interfaces, effective selective adsorption on these interfaces, effects of adsorption on adsorbant bond strength, and understanding of the molecular mechanisms involved therein. This is a fundamental study with strong implications for any future projects involving miniaturized sensors, gas separation, or high-performance catalytic conversion utilizing ILs and/or SCs. This systematic research is being conducted using state-of-the-art electrochemical, spectroscopic, surface science, and computational chemistry methods. The main goals of this project are to achieve a greater fundamental understanding of small molecule adsorption at IL/SC interfaces and to explore new chemistry and physics on these interfaces. ILs generate a very unique solid-like interface; consequently, they can generate extremely high electric fields and induce exceptionally large charge densities at the solid/liquid interface. The electric double layer (EDL) charge density can be much higher than traditional field-effects and allows for new levels of electrostatic modulation to be accessible. The pure ionic structure of IL itself also brings an electrostatic environment, which can potentially be manipulated for facilitating certain small molecule activation. However, electrified IL/electrode interfaces, especially SC's, with adsorbed gas molecules have not been either theoretically or experimentally studied. Here the strong interaction granted by SC with the tunability of IL interfaces are exploited in order to achieve and evaluate gas adsorption that is both sensitive and selective by systematically studying adsorption behavior in the IL environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.