CAS: Collaborative Research: Steering Proton-Coupled Electron Transfer Processes for Energy Conversion at the Metal Electrode/Porous 3D Material Interface

University Of Massachusetts Boston, Dorchester MA

Investigators

Abstract

With the support of the Chemical Catalysis program in the Division of Chemistry, Professors Matthias Waegele and Junwei (Lucas) Bao of Boston College, and Professor Mariam Ismail of the University of Massachusetts, Boston are studying how to precisely modify electrodes to control electrocatalytic reactions for energy storage. Electrocatalytic processes can store electrical energy from renewable energy sources in the form of liquid or gaseous fuels from abundant, renewable feedstocks such as carbon dioxide or biomass. A principal hurdle for the adoption of this technology is the poor product selectivity of these reactions. These reactions are complex and occur at an interface involving a liquid (the electrolyte) and a solid (the electrode). In this work, the project team will modify this interface, and thus the electrocatalytic activity, by coating the electrodes with a special class of porous material known as metal-organic frameworks (MOFs). The project team will use spectroscopy and advanced computer simulations to gain molecular-level insights into the effects of the MOF overlayers on three model reactions that are central for renewable fuel synthesis: The conversion of water to hydrogen, the conversion of carbon dioxide to carbon monoxide, and conversion of biomass to valuable chemicals and fuels. The results of this research will provide insight into the control of selectivity of electrocatalytic reaction. Further, the team will engage in synergistic activities aimed at promoting the recruitment and retention of underrepresented groups in STEM. Specifically, the team will involve female high-school students and underrepresented undergraduate minority students in this research as part of a summer program, which will expose the participants to state-of-the-art renewable energy research in the areas of synthesis, analytical chemistry, and simulation techniques. On this project, Matthias Waegele and Junwei (Lucas) Bao of Boston College and Mariam Ismail of the University of Massachusetts, Boston are studying and designing 3D active sites at the metal electrode/porous 3D material interface to facilitate desirable reaction pathways of proton-coupled electron transfer (PCET) processes for energy storage and conversion. To this end, the team will coat metal electrodes (Pt and Au) with crystalline metal-organic framework (MOF) overlayers and investigate the effects of the MOF overlayers on PCET processes. Through systematic variation of the inorganic nodes and organic linkers of the MOFs, the team will aim to understand the effect of the MOF’s chemical and physical properties on PCET. The project will focus on the hydrogen evolution reaction (HER) and the reduction of carbon dioxide to carbon monoxide. Vibrational and Raman spectroscopies will be used to characterize the metal electrode/MOF interface under catalytic conditions. Key properties to be extracted from these measurements will include the interfacial pH, electric double layer charging, MOF-intermediate interactions, interfacial water structure, and local structure of the MOF at the metal surface. Computer simulations will map minimum-energy reaction pathways. On the basis of these investigations, the project aims to establish robust interfacial property-reactivity relationships. Such design rules would serve to guide the choice of synergistic 3D material, electrolyte, and reaction conditions to steer PCET reactions in aqueous electrolytes, and thereby also support the discovery of efficient and selective pathways for renewable fuels formation. 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.