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.
