(6ha) Nano Engineering with X-Ray through Infrared Spectroscopy (NEXIS)

1^st Year Postdoctoral Fellow

Keywords: 2D transition metal oxides (TMOs), bench-scale X-ray absorption fine structure (XAFS), catalysis, collaboration

Research Interests:

2D nanomaterials--especially beyond graphene--are the latest wave in the nanomaterial “gold rush” due to the promise of exciting chemical and electronic properties, high tunability, and amenable geometry over their 0D and 1D counterparts. In particular, manipulation of 2D transition metal oxide (TMO) systems through compositing, doping, and functionalization would be especially useful to fields such as catalysis, photovoltaics, transistors and more where ceramics and semiconductors are already implemented. However, researchers in the 2D TMO field face major challenges: attaining precise structure control and determining how numerous factors affect macroscopic properties. Only through a thorough fundamental scientific understanding can we hope to distinguish truly promising technologies from “fool’s gold.”

My primary research focus is to engineer new 2D TMO systems by developing new synthesis techniques to precisely control their structure, to study their growth and property relationships using state of the art ex situ and operando XAFS and FTIR spectroscopy, and to boldly use these materials as catalysts and more to solve problems in energy, the environment, and beyond.

Research Experience:

PhD Dissertation: “Tuning the Optical and Catalytic Properties of CuO and Fe₂O₃ Nanosheets for CO₂ Conversion”

Under the supervision of Prof. Lisa D. Pfefferle in the Department of Chemical and Environmental Engineering at Yale University I combined synthesis, characterization, and application to better understand and implement 2D TMO systems. I tuned the properties of copper oxide nanosheets and related showed that band gap could be a descriptor for reactivity. I re-pioneered hard-templating in order to synthesize ultra-thin iron oxide nanosheets for CO₂ reduction. I developed new methods for functionalizing copper oxide nanosheets with organic small molecules and showed a drastic increase in the material’s hydrophobicity and stability. Throughout my work I utilized a collection of spectroscopic techniques and I collaborated with computationalists to better understand 2D TMOs while improving the modelling of them.

Postdoctoral Research:

Under the supervision of Prof. Shu Hu in the Department of Chemical and Environmental Engineering at Yale University I extended my knowledge of synthesis, spectroscopy, and electrochemistry. I used,

• operando PM-IRRAS to investigate temperature dependent methane electroxodation
• in stiu XAFS to study the local atomic structure of ALD grown TiMnOx for selective H₂O₂ electrodes
• Semiconductor synthesis: CdSe/ZnS quantum dot – porous GaN composites for fabricating µLEDs
• Catalysis: BaTiO₃ to study polarization chemistry for high frequency switching catalysis

Future Direction:

As a faculty member I will draw on my experiences from my PhD and post doc to lead a group focused on controlled 2D nanometal oxide synthesis, in situ spectroscopic characterization, and heterogenous catalysis. I will expand the breath and depth of 2D TMO understanding by developing hard templating and functionalization to synthesize new 2D TMOs systems; use in situ X-ray absorption Fine Structure (XAFS) and Fourier-Transform Infrared (FTIR) spectroscopies to understand adsorption, the solid-liquid interface, and map growth and catalytic reaction pathways on material’s surface; and by establishing structure-property relationships I will tune these materials for CO₂ reduction and CH₄ oxidation. Of particular interest are synthesizing bimetallic 2D TMO composites, controlling facet exposure, and tuning the number and type of defects present. CO₂ and CH₄ conversion reactions are both important due to the industry relevance of these molecules, the difficulties in their capture and transport, their high stability leading to poor conversion and selectivity in catalytic reactions. The tunability and reactivity of 2D TMOs make them perfect candidates to face the challenge of converting CO₂ and CH₄ into transportable, storable, value added liquid products.

Beyond catalysis, oxide nanomaterials have seeped into nearly every field, from membranes to medicine. My vision for the NEXIS lab is to not only be an engine for nanomaterial engineering and development, but also a hub for collaboration and multidisciplinary research. The NEXIS lab will be home to advanced spectroscopic instruments, such as bench-scale XAFS, which will enable atomic scale characterization only previously achievable using synchrotron radiation. Using existing and future connections, I will work with collaborators in academia and industry, experimentalists and computationalists, to realize a superior understanding of materials and their structure-property relationships in order to enable their implementation.

Teaching Interests:

My goal as an educator is to inspire, challenge, and support students through diverse assignments in order to impart fundamental scientific knowledge while building in them essential skills for a multitude of professions.

My multidisciplinary and collaborative experience and views are not limited to my research. Throughout my career I have TAed for Separations and Purification Processes, Multivariable Calculus, and Fluid Mechanics hosting study session, grading assignments, and guest lecturing on a few occasions. Additionally, I designed my own classes and taught subjects such as philosophy and creative writing as a volunteer teacher in Yale’s Sprout and Splash programs. In the lab, I have mentored over 13 undergraduate and high school students who have gone on to become graduate students and lead successful lives. As an educator I am excited to bring my experiences to the classroom balancing tests with other collaborative and interactive assignments in order to foster important skills such as technical writing and public speaking. I feel prepared to teach fundamental chemical engineering classes and look forward to teaching laboratory and collaborative design style classes.

Proposal Writing Experience: Petroleum Research Fund, Samsung: The Global Outreach Program, NSF-CAT, NSF-DMREF, Army Research Office (funded), EPA-STAR

Selected Publications:

1. Fishman, Z.S., Rohr, J.A., He, Y., Batista, V.S., Pfefferle, L.D., Hu, S. “Fine tuning the optical and electronic properties of CuO nanosheets using organic functionalization.” in preparation

2. He, Y.*, Fishman, Z.S.*, Yang, K., Ortiz, B., Goldsamt, J., Batista, V.S., Pfefferle L.D., “Hydrophobic CuO Nanosheets Functionalized with Organic Adsorbates” Am. Chem. Soc., 140(5), pp 1824–1833 (2018). *equal author contributions

3. Zucker, I., Werber, J.R., Fishman, Z.S., Hashmi, S.M., Gabinet, U.R., Lu, X., Osuji, C.O., Pfefferle, L.D., Elimelech, M., “Loss of Phospholipid Membrane Integrity Induced by Two Dimensional Nanomaterials” Sci. Technol. Lett., 4 (10), pp 404–409 (2017).

4. Fishman, Z.S., He, Y., Yang, K., Rudshteyn, B., Lounsbury, A., Zhu, J., Zimmerman, J.B., Batista, V.S., Pfefferle, L.D., “Hard Templating Ultrathin Polycrystalline Hematite Nanosheets and the Effect of Nanodimension on CO₂ to CO Conversion via the Reverse Water Shift Reaction” Nanoscale 9, 12984-12995 (2017).

5. Fishman, Z.S., Rudshteyn B., He, Y., Liu, B., Chaudhuri, S., Askerka, M., Haller, G.L., Batista, V.S., Pfefferle, L.D., “Fundamental Role of Oxygen Stoichiometry in Controlling the Band Gap and Reactivity of Cupric Oxide Nanosheets” Am. Chem. Soc., 138(34), 10978–10985 (2016).