MSE Colloquium: Jill Wenderott, Northwestern University

Jill Wenderott
Northwestern University
Postdoctoral Researcher, Materials Science Division, Argonne National Laboratory

Oxynitride materials for use in (photo)catalysis applications

Heteroanionic materials, compounds comprised of multiple anionic species in single phases, offer broad opportunity for new and potentially superior functionalities. Notably, transition metal oxynitrides – like the molybdenum (Mo-O-N) and tantalum (Ta-O-N) systems – have been increasingly investigated for their tunable electronic and optical properties. Molybdenum nitrides (γ-Mo2N, MoN) are often synthesized via ammonolysis, in which gaseous ammonia is supplied and reacts with molybdenum oxide powders at elevated temperatures. Insights gleaned from probing ammonolysis reaction pathways indicate that numerous factors influence the phase fraction, chemical composition, and surface area of the final nitride product, and so pathway control can allow for both chemical and physical tunability of the final product. In the first section of this talk, the reaction pathway to γ-Mo2N illuminated via in situ powder X-ray diffraction is presented, and the structure and composition of the product is clarified to reveal its identity as a hydrogen-incorporated molybdenum oxynitride. Leveraging findings from in situ studies, exotic molybdenum bronze precursors are utilized to produce phase pure molybdenum oxynitrides at the lowest reaction temperatures and highest surface areas reported in literature to date, relevant for their application in catalysis. In the second section of this talk, tantalum oxynitrides (TaON) primarily in thin film forms are presented. TaON has been realized as a desirable candidate for visible light driven photocatalysis and antibiofilm coatings, though functional properties of various TaON polymorphs as well as thin film preparation strategies remain relatively unexplored. Reaction pathways to two TaON polymorphs and visible light photodegradation performance are first compared. Two thin film approaches – graded pulsed laser deposition to target synthesis parameters for single crystal TaON and atomic layer deposition to create conformal TaOxNy coatings – are then discussed as strategies for further investigation and application of these materials.

Bio

Jill K. Wenderott is currently a postdoctoral appointee at Argonne National Laboratory in the Materials Science Division. Prior to this appointment, she was a postdoc in the Department of Materials Science and Engineering at Northwestern University investigating heteroanionic oxynitride materials for catalysis applications under the supervision of Prof. Sossina Haile. Jill completed her B.S. in Physics at the University of Kansas (2014) before receiving her Ph.D. in Materials Science and Engineering from the University of Michigan (2018) in Prof. Peter Green's group. Her Ph.D. focused on understanding the connection between conjugated polymer thin film morphology and electronic properties using advanced atomic force microscopy techniques. Jill was a Rackham Merit Fellow at the University of Michigan, and recently as a postdoc, her international team was awarded the 2020 American Physical Society Innovation Fund to support their organization, Women Supporting Women in the Sciences (WS2).