(6fb) Engineering Nanoscale Materials and Interfaces for Sustainable Energy and Chemical Processes

Interfaces are critical elements of many technologies and chemical processes, particularly in the areas of clean energy and efficient separations. My proposed research focuses on the rational, molecular level design of functional interfaces and materials by bringing together cutting-edge tools and concepts from interface science, electrochemistry, and nanotechnology. These studies will enable technologies to address critical needs, from energy efficient water purification, to next generation batteries based on earth-abundant chemistries.

For decades, colloid and interface science has been driven by equilibrium experiments and ideas. Yet, many important chemical processes, like electrochemical energy conversion, inherently operate under far-from-equilibrium conditions, where equilibrium intuition breaks down. These processes are dynamic, controlled by cooperative molecular interactions which span many nanometers in distance, and often hinge on fleeting metastable states. The spatiotemporal scales on which these processes operate remain inaccessible to molecular simulation, and few experimental techniques can directly measure dynamic, molecular level processes at interfaces. This presents a major challenge for targeted design of surfaces and nanoscale materials.

I propose to address this challenge by leveraging my perspective and expertise in molecular force spectroscopy, electrochemistry, and advanced microscopy to measure and control dynamic processes at non-equilibrium interfaces. I am particularly excited to explore how ionic and electronic transport can be controlled at solid-liquid and liquid-liquid interfaces using dynamic electric and magnetic fields.

My proposed research program will address the following aims:

1. Engineering confined solid-liquid interfaces for energy storage and conversion.

Understanding how nanoscale confinement influences electrochemical reaction dynamics, barriers, and pathways will enable advanced electrolytes and interfaces for next generation batteries.

2. Creating electroactive nanomaterials to achieve energy efficient separations.

Studying how dynamic electric fields drive molecular transport, adsorption, and charge transfer in nanoporous materials will enable efficient CO₂ adsorption, water purification, and enantiomeric separations.

3. Controlling the dynamics of soft materials and interfaces with magnetic fields.

Magnetic interactions are conventionally neglected in colloid science. Designing magnetic soft materials to exhibit field dependent interface energies will permit magneto-responsive emulsions for separations, phase transfer catalysis, and water treatment.

Research Experience:

I apply quantitative experiments and systematic tuning of molecular structures to establish design principles for materials and interfaces. During my Ph.D., I developed deep expertise in colloid and interface science, electrochemistry, and materials synthesis. In my primary project, I combined surface forces and electrochemical methods to discover that more than 99.99% of the ions that comprise ionic liquids behave as neutral pairs (1). This contrasted prior expectations, which suggested that most ions were freely dissociated. From these results, we proposed a new way of envisioning concentrated electrolytes to guide the design of advanced ionic liquids and battery electrolytes (1–3). I used analogous approaches to assess the role of electrostatics in mussel protein adhesion. We found that dynamic ionic bonds are critical for marine bio-adhesion and unveiled new stable functionalities to expand the toolbox for designing underwater adhesives (4).

During my postdoctoral tenure, I broadened my expertise towards nanomaterials synthesis, nanofabrication, and advanced microscopy. At Stanford, I studied diamond nanomaterials for single-molecule fluorescence. A poor understanding of nucleation has been a major hurdle facing the synthesis of high quality diamond for many applications. By mapping the nucleation landscape using molecular seeds, we found that diamond nucleation during chemical vapor deposition is a non-classical process with a barrier that is four orders of magnitude lower than prior classical estimates (5). We also developed methods to pattern fluorescent color center crystal defects in diamond lattices with nanoscale precision. Both thrusts address key challenges to enable using diamond in molecular sensing, bio-imaging, and quantum computing.

Selected Publications:

1. Gebbie MA, Valtiner M, Banquy X, Fox ET, Henderson WA, Israelachvili JN. Ionic liquids behave as dilute electrolyte solutions. PNAS 110, 9674–9679 (2013). DOE Basic Energy Sciences Research Highlight, June 2013
2. Gebbie MA, Dobbs HA, Valtiner M, Israelachvili JN. Long-range electrostatic screening in ionic liquids. PNAS 112, 7432–7437 (2015).
3. Gebbie* MA, Smith AM, Dobbs HA, Lee AA, Warr GG, Banquy X, Valtiner M, Rutland* MW, Israelachvili* JN, Perkin* S, Atkin* R. Long range electrostatic forces in ionic liquids. Chem. Commun. 53, 1214–­­1224 (2017). * - Co-corresponding authorship, Invited Feature Review
4. Gebbie* MA, Wei* W, Schrader AM, Cristiani T, Waite JH, Israelachvili JN. Tuning underwater adhesion with cation-π interactions. Nature Chemistry 9, 473–479 (2017). * - Equal contribution, Highlighted in Chemical & Engineering News, February 2017
5. Gebbie MA, Ishiwata H, McQuade PM, Petrak V, Taylor A, Dahl JE, Carlson RMK, Fokin AA, Schreiner PR, Shen ZX, Nesladek M, Melosh NA. Experimental measurement of the diamond nucleation landscape reveals classical and non-classical features. In revision.

Teaching Interests:

I have broad interests in teaching core chemical engineering courses, especially transport, fluids, thermodynamics, interfaces, and polymers. I am also excited to develop a graduate course on applying concepts from colloid and interface engineering to sustainability and energy science.