Arturo Medina

Advisor: Prof. Faisal M. Alamgir

will propose a doctoral thesis entitled,

Work Function–Driven Interfacial Electronic Structure and Field Modulation in 2D Metal/Graphene Catalysts

On

Tuesday, September 9, 2025

11am - 1pm 

MRDC Conference Room 3510

or virtually via Microsoft Teams: 

Join meeting here

Committee:

Prof. Faisal M. Alamgir – School of Materials Science and Engineering (advisor)

Prof. Seung-Soon Jang – School of Materials Science and Engineering

Prof. Eric Vogel – School of Materials Science and Engineering

Prof. Mark D. Losego – School of Materials Science and Engineering

Prof. Martin Mourigal – School of Physics

Prof. Hicham Idriss – KIT Institute of Functional Interfaces

Abstract

Understanding and controlling catalytic activity at the atomic scale requires descriptors that unify electronic and structural effects across diverse material systems. This work advances the work function (WF) as a central descriptor that links charge transfer, strain, and catalytic reactivity in two-dimensional (2D) metal/graphene heterostructures. Using ultraviolet photoelectron spectroscopy (UPS), X ray photoelectron spectroscopy (XPS), and X ray absorption spectroscopy (XAS), substrate induced changes in lattice strain and charge redistribution are tied to shifts in WF, on the path to establishing a transferable framework that bridges structure and electronic behavior. Furthermore, experimentally combined data with an emergent density functional theory (DFT) based model enable predictive maps of the electric potential where hydrogen evolution (HER) and carbon dioxide reduction (CO₂RR) occur in Ir/Gr/M systems (Ir refers to iridium metal, Gr refers to single-layer graphene and M to a metallic substrate). As a validation of the close connection between the theoretical model and real systems, we have experimentally verified that, the Ir/Gr/M catalysts are poor for CO₂RR but favorable for HER, as predicted by theory. In the proposed work, we will explore whether WF can directly predict the electric potential where HER and CO₂RR occur for Ir/Gr/M and related systems.

The intrinsic electric fields of ferroelectric supports introduce a new axis of control for catalysis. By integrating ultrathin platinum (Pt) overlayers with graphene on periodically poled lithium niobate (PPLN), alternating ±180° ferroelectric domains are tested for their ability to induce domain specific shifts in WF, electronic structure, and catalytic behavior. Preliminary Raman, piezoresponse force microscopy (PFM), and XPS measurements confirm that polarization fields penetrate through graphene and persist even after Pt growth, while synchrotron-based C-K edge mapping reveals domain dependent π* undulations consistent with ferroelectric modulation. Taken together, these results motivate the proposed work, which will establish a comprehensive framework in which structure, WF, and reactivity are quantitatively linked, and where active field tunable catalysis can be realized. The proposed outcome is a predictive descriptor to performance map that unifies structural, electronic, and field effects, laying the foundation for the rational design of graphene based heterostructures as tunable, energy efficient catalysts for sustainable energy conversion.