Advanced Three-Dimensional Non-Precious Metal Catalysts with Tunable Active Sites for Fuel Cells

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Since their birth in the last century, polymer electrolyte membrane fuel cells (PEMFCs) have been highly touted as the most promising technology to meet the ever-increasing energy demands of modern society while addressing environmental concerns. However, the high cost and poor durability of the platinum (Pt) based catalysts at cathode continue to impede widespread commercialization of PEMFCs. As a desirable alternative to Pt-based catalysts, non-precious metal catalysts (NPMCs) towards oxygen reduction reaction (ORR) were proposed. After years of progress, the activity and durability of NPMC-based cathodes are still far from providing a practical solution for PEMFC systems. To advance NPMC research significantly, challenges related to the active sites must be addressed. These challenges include low active site density, low active site accessibility, and uncertain active site structure with low inherent activity. We propose to overcome these challenges through the rational design of NPMCs. Specifically, three series of unique three-dimensional NPMCs (3D-NPMCs), with tunable active site density, accessibility, and inherent activity, will be prepared from 3D-precursors using new techniques, such as atomic dispersion of active sites. We will optimize ORR activity and durability with detailed physiochemical and electrochemical characterizations and theoretical calculations and elucidate the underlying factors related to the active sites. Promising 3D-NPMCs will be fabricated into unique 3D-architectured NPMC cathodes, which will be integrated and investigated extensively in a single cell PEMFC. The optimal electrode properties and preparation parameters will be determined via both experiment and numerical modeling. With further extensive durability tests in PEMFC and associated post-testing characterizations, the mechanism of performance degradation and active site evolution during long-term operation will be elucidated and mitigation strategies and diagnosis techniques will be developed accordingly. This novel research will advance the technical and scientific knowledge for the rational design of 3D-NPMCs with tunable active sites and unique 3D-NPMC electrodes, influencing material science, electrochemistry, nanotechnology, and clean energy technology. It also will reduce costs for fuel cell manufacturing and distribution companies, as well as related fuel cell automobile companies. Finally, the HQP trained in this work will be exposed to top-quality personnel from the applicant's research group and collaborators in academia and industry. They will have access to world-class equipment to conduct their projects and degree programs. The technology, new knowledge, and trained HQP will benefit the Canadian knowledge-based economy in the energy sector while being of interest to material scientists and engineers, chemical engineers, nanotechnologists, and electrochemists.