Eliminating precious metals from hydrogen fuel cells and electrolyzers

政府间气候变化专门委员会估计，如果地球变暖2摄氏度而不是1.5摄氏度，面临水资源短缺的人口将增加一倍，暴露在极端热浪中的人口将增加15亿，感染疟疾和登革热等媒介传播疾病的风险将大幅增加。要将全球变暖控制在1.5摄氏度以内，需要迅速而深远地过渡到由可再生电力供应的电网、零排放车队，以及大幅减少与工业相关的二氧化碳排放。增加零排放汽车和可再生能源在电网中的份额，将需要开发电化学能源系统，以化学燃料的形式储存电力，可用于工业和交通部门。由于氢的零排放特性，氢已被证明是一种优秀的化学燃料，加拿大的氢战略估计，到2050年，氢可以满足高达24%的全球能源需求。氢质子交换膜燃料电池(PEMFC)汽车已经商业化，几个质子交换膜水电解槽(PEMWE)发电项目正在进行中，以展示其用途。然而，商用的质子交换膜燃料电池和质子交换膜有两个共同的弱点：a)使用稀有和昂贵的铂族金属(PGM)催化剂，如铂和铱，以及b)使用氟化膜。这些弱点使得这些系统的成本对于许多应用来说都贵得令人望而却步。燃料电池和电解槽在碱性条件下运行，允许使用非贵金属电催化剂，如镍和银，以及更便宜的金属，用于多孔层和双极板，因为在高pH条件下腐蚀性较小。此外，阴离子交换膜(AEMS)大多以碳氢化合物为基础，从而消除了PEMFC中使用的氟化化学品，这些化学品也很昂贵，并构成健康和环境风险。自2016年以来，几种AEMS已经显示出良好的离子导电性和稳定性，从而为新型阴离子交换膜燃料电池(AEMFC)和电解槽(AEMWE)的发展创造了机会；然而，AEMFC电极中的水积累，以及缺乏详细的表征和模拟工具来研究无PGM的AEMFC和AEMWE，到目前为止阻碍了进一步的发展。AEMFC和AEMWE提供了变革性的材料成本节约的潜力，因此被视为PEMFC和PEMWE的高回报替代品。拟议的计划旨在开发计算机辅助设计和实验表征、测试和验证工具，以优化：a)低和/或零PGM AEMWE的电极组成；以及b)AEMFC中的水传输。它还将在碱性电化学系统的实验制造、表征和测试以及数值模拟领域培训高素质的人员。

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.