Eliminating precious metals from hydrogen fuel cells and electrolyzers

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The Intergovernmental Panel on Climate Change estimates that if the planet warms by 2 °C instead of 1.5 °C, twice as many people will face water scarcity, 1.5 billion more people will be exposed to extreme heat waves, and the risk of contracting vector-borne diseases, such as malaria and dengue fever, will substantially increase. Limiting global warming to 1.5 °C requires a rapid and far-reaching transition to an electrical grid supplied by renewable electricity, a zero-emission vehicle fleet, and a substantial reduction of industry related carbon dioxide emissions. Increasing the share of zero-emission vehicles and renewable energy in the grid will necessitate the development of electrochemical energy systems to store electricity in the form of chemical fuels that can be used in industrial and transportation sectors. Hydrogen has been shown to be an excellent chemical fuel due to its zero-emission nature, with the Hydrogen Strategy for Canada estimating that hydrogen could meet up to 24% of global energy demand by 2050. Hydrogen proton exchange membrane fuel cell (PEMFC) vehicles are already commercialized, and several power-to-gas proton exchange membrane water electrolyzer (PEMWE) projects are underway to demonstrate their use. However, commercial PEMFCs and PEMWEs share two common weaknesses: a) the use of rare and expensive platinum-group metal (PGM) catalysts, such as platinum and iridium, and b) the use of fluorinated membranes. These weaknesses make the cost of these systems prohibitively expensive for many applications. The operation of fuel cells and electrolyzers in alkaline conditions allows the use of non-noble electrocatalysts, such as nickel and silver, and cheaper metals for porous layers and bipolar plates due to the less corrosive environment at high pH. Further, anion exchange membranes (AEMs) are mostly hydrocarbon-based, thereby eliminating the use of fluorinated chemicals used in PEMFCs, which are also expensive and pose health and environmental risks. Since 2016, several AEMs have shown promising ion conductivity and stability, thereby creating an opportunity for the development of novel anion exchange membrane fuel cells (AEMFCs) and electrolyzers (AEMWEs); however, water accumulation in AEMFC electrodes, and a lack of detailed characterization and simulation tools for PGM-free AEMFCs and AEMWEs has thus far hampered further development. AEMFCs and AEMWEs offer the potential for transformative savings in material costs and are, therefore, viewed as a high-reward alternative to PEMFC and PEMWE. The proposed program aims at developing computer-aided design and experimental characterization, testing, and validation tools to optimize: a) electrode composition of low- and/or zero-PGM AEMWEs; and b) water transport in AEMFCs. It will also train highly qualified personnel in the areas of experimental fabrication, characterization and testing, and numerical simulation of alkaline electrochemical systems.