CAREER: Engineered Oxide Heterointerfaces With Tunable Vacancy Distributions

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: Many energy conversion and storage applications require chemical reactions along some critical surface or interface to effectively operate. Replacing scarce, expensive noble-metal materials with abundant, cheap, efficient complex metal-oxide alternatives remains a primary challenge facing energy conversion. Missing oxygen atoms in the structure of these alternative oxide materials dictate their functional properties. This research uses novel microscopy methods and classic semiconductor analysis to visualize and quantify the location and amount of missing oxygen atoms across the critical interface under the operating conditions of actual energy conversion systems, in real time. Understanding the fundamental mechanisms of how missing atoms affect energy conversion at the interface is vital to rapidly advancing the development of devices such as fuel cells and electrolyzers. This work trains undergraduate and graduate students across the disciplines of materials science, surface science, and electrochemistry for placement in the energy conversion/storage, electronics, and nanotechnology sectors. This project also includes a fully integrated educational component where an undergraduate student team develops microscopy modules that are demonstrated in both senior capstone and graduate level courses using a portable atomic force microscope. This "flipped" instruction model also allows the undergraduate team to extend their module demonstrations to summer high school programs, and on social media, to inspire underrepresented groups to pursue science and engineering as exciting and worthwhile academic and career pathways. TECHNICAL DETAILS: Oxygen vacancy-mediated reduction, dissociation, or incorporation mechanisms often contribute to the rate-determining step in solid-state electrochemical energy conversion processes. This project combines transformative in situ scan probe microscopy methods with electrostatic analysis to directly observe, and quantify, critical high temperature vacancy-mediated ionic transport phenomena across electroactive oxide interfaces under extreme environmental perturbation, at the nanoscale. The goal of this research is to understand how vacancy distributions evolve across electroactive oxide interfaces as a function of work function engineering, mismatch strain, and/or compositional gradients. These activities train university student researchers in high temperature in situ microscopy and sample preparation to push the frontier of experimental methodology. By directly observing vacancy redistribution across electroceramic interfaces in real time, this project is establishing the structure-property principles necessary for the realization of mechanically-stable, catalytically-active interfaces and advancement of next-generation electrochemical energy conversion systems. 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.