Non-Platinum Group Metal OER/ORR Catalysts for Alkaline Membrane Fuel Cells and Electrolyzers

Statement of the problem or situation that is being addressed: A major challenge in successful development of unitized regenerative fuel cells (URFCs) is the bifunctional air/oxygen electrode. In proton exchange membrane-based systems, the number of stable elements at electrolysis potentials is extremely limited, restricting the oxygen evolution reaction (OER) / oxygen reduction reaction (ORR) catalyst to PGM-containing compounds. Proton OnSite and Rutgers University therefore propose a non-PGM, bifunctional OER/ORR catalyst system for alkaline exchange membrane (AEM)-based unitized regenerative fuel cells. Our proposal aims to bring together the advances in nonnoble electrolyzer catalysts developed at Rutgers, and Protons expertise in AEM electrolyzers, regenerative fuel cells, stack development and integration. The advantages of alkaline URFCs are as follows: Lower cost non precious metal catalysts Lower cost bipolar plate components Lower cost balance of plant components. Objective and approach for Phase 1 project: Phase 1 will focus on electrochemical synthesis, analysis and application of synthesized catalyst powders with the objective of obtaining maximum stability and performance while eliminating PGM content on the oxygen side of the cell. Furthermore, concurrent cell development will be conducted in order to characterize and enable fuel cell and electrolysis on a single cell platform by optimizing catalyst ionomer ratio and loading, as well as flow properties of water through the anodic and cathodic compartments of the URFC. Electrocatalysts developed at Rutgers have been previously evaluated by Proton in AEM electrolysis cells, with performance on par with Protons state of the art precious metal catalysts. To be successful as a URFC these electrodes will have to perform the additional catalytic tasks of ORR in fuel cell mode. Preliminary data from Rutgers shows promise in this regard, and there is much to more to be gained by further catalyst optimization and the utilization of transition metal supports. The end deliverables of the Phase 1 effort will be an understanding of catalyst-ionomer-polymerelectrode structure-property relationships necessary to develop a high performance alkaline membrane URFC based on a non- PGM oxygen electrode. Commercial Applications and Other Benefits: For commercial energy markets, the main roadblock to implementation of regenerative fuel cells is the capital and operating cost of the PEM electrolyzer and fuel cell stacks. Alkaline exchange membrane-based fuel cells and electrolyzers offer a much more cost effective platform due to the potential use of non-noble metal catalysts and cheaper stack components. Further, a combined fuel cell and electrolyzer system, a so-called unitized regenerative fuel cell (URFC), decreases the total amount of stack and BoP components. Combining the fuel cell and electrolyzer stacks and integrating the balance of plant has the potential to result in significant additional cost savings to enable these markets. The electrode developments being pursued here should be easily integrated into the full scale stack as elements are proven. There is nearly 100 GW of wind energy generation in Europe and limitations are already being experienced in grid management, requiring energy storage. Hydrogen provides a dispatchable energy storage media and can serve an existing need to capture stranded wind energy resources. Next generation products could also include subassemblies and systems for telecommunications backup power systems, and for air independent energy storage devices for underwater and high altitude unmanned platforms. Key Words: alkaline exchange membranes, electrolysis, fuel cell, hydrogen generation, regenerative fuel cell, energy storage, bi-functional catalysts Summary for Members of Congress: This project aims to develop a more efficient bidirectional AEM cell stack which can ultimately be deployed for low cost and lightweight energy storage requirements. The innovation will provide a cost effective and simpler system approach to generating hydrogen via electrolysis, and converting it back to electricity in fuel cell mode.