Title: Catalytic Behavior of Molecular Polyoxometalates and Transition Metal Oxides Towards Hydrogenation Reactions via Electrochemical Proton Coupled Electron Transfer

Abstract: Electrochemistry is a powerful tool that can be used to manipulate the equilibrium of redox reactions by an order of magnitude of 10100 under ambient conditions. Since about 90% of all processes in the chemical industry are catalytic, electrocatalysis is an emerging technique to find sustainable routes to chemical production with the use of renewable energy. However, most industrial processes use thermal catalysis. Two key reasons limiting the industrial use of electrocatalysis are the existing knowledge gap in the fundamental phenomena governing electrocatalysis, and most high-performing electrocatalysts are the platinum-group metals which are expensive. A key fundamental principle underlying the energy transformations in chemical and biological systems is the proton coupled electron transfer (PCET), which is energetically more favorable than sequential electron/proton transfer steps.

The overarching goal of this proposal is to understand the catalytic behavior of polyoxometalates and extended metal oxides, based on non-precious transition metals, towards reduction reactions via electrochemical PCET.  This work is divided into two broad objectives. Objective 1 focuses on comparing the catalytic performance of the polyoxometalates and extended transition metal oxides towards electroreduction reactions governed by PCET via the metrics of onset potential (indicative of overpotential required) and desired product selectivity for a chosen electroreduction chemistry. The successful completion of this objective will further our insights into designing better non-precious metal catalysts for industrially relevant processes. Objective 2 focuses on the application of using a transition metal-based catalyst as a PCET mediator for thermally activated hydrogenation or hydrodeoxygenation chemistries which would eliminate the need to use hydrogen gas. A tungsten oxide film with electrochemically inserted hydrogen is proposed to act as a mediator for hydrogen transfer for the reduction reactions. Successful completion of this objective will provide evidence to demonstrate that electrocatalytic hydrogen insertion in extended metal oxides can be used to replace precious metals required for hydrogen dissociation and spillover for thermally activated reduction chemistries.

Overall, this work addresses the key challenges in electrocatalysis by focusing on non-precious catalysts and understanding their performance based on the PCET principle as a contribution to furthering the industrial application of electrocatalysis.

Chair:

Dr. James McKone

Department of Chemical and Petroleum Engineering, University of Pittsburgh

Co-Chair:

Dr. Chris Wilmer

Department of Chemical and Petroleum Engineering, University of Pittsburgh

Committee Members:

 Dr. Götz Veser

Department of Chemical and Petroleum Engineering, University of Pittsburgh

Dr. Susan Fullerton

Department of Chemical and Petroleum Engineering, University of Pittsburgh

Dr. Ellen Matson

Department of Chemistry, University of Rochester