Single Atomic Iron Site Catalysts via Benign Aqueous Synthesis for Durability Improvement in Proton Exchange Membrane Fuel Cells
Single Atomic Iron Site Catalysts via Benign Aqueous Synthesis for Durability Improvement in Proton Exchange Membrane Fuel Cells
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DOI：
10.1149/1945-7111/abf014
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发表时间：
2021-04
影响因子：
3.9
通讯作者：
Mengjie Chen;D. Cullen;S. Karakalos;Xiner Lu;Jiang Cui;A. J. Kropf;H. Mistry;K. He;D. Myers-D.-Myer
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文献类型：
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作者：
Mengjie Chen;D. Cullen;S. Karakalos;Xiner Lu;Jiang Cui;A. J. Kropf;H. Mistry;K. He;D. Myers-D.-Myer
原子分散的铁氮碳（Fe-N-C）催化剂已成为燃料电池中取代昂贵的贵金属催化剂的有希望的候选材料，但仍面临着一些重大挑战，如场地密度和耐用性不足。在此，我们报告了一种在水溶液中自组装的方法，以开发一种在酸性电解质中具有高氧还原反应（ORR）活性和稳定性的原子分散铁催化剂。通过高分辨率透射电子显微镜（HR-TEM）、x射线吸收光谱（XAS）和高角度环形暗场扫描透射电子显微镜（HAADF-STEM）的研究发现，这种良性的水相合成策略有助于在爆米花状多孔石墨碳基体中形成均匀的原子氮配位铁位点。这些催化剂性能有助于改善ORR的动力学电流密度和质量输运。通过控制合成化学，系统地研究了结构与性能之间的关系。铁含量是最关键的材料性质，可以调节催化剂中的位点密度和石墨碳结构，影响催化活性和稳定性。在酸性水电解质和膜电极组件中测试了增强的性能和耐久性。
Atomically-dispersed iron-nitrogen-carbon (Fe–N–C) catalysts have arisen as promising candidates for replacing the costly precious metal catalysts in fuel cells but still face some grand challenges, such as insufficient site density and durability. Herein, we report a self-assembly method in an aqueous solution to develop an atomically-dispersed iron catalyst with high oxygen reduction reaction (ORR) activity and stability in acidic electrolytes. As determined by high-resolution transmission electron microscopy (HR-TEM), X-ray absorption spectroscopy (XAS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), this benign aqueous synthesis strategy facilitates the formation of homogeneous atomic nitrogen-coordinated iron sites embedded in a popcorn-like porous graphitic carbon matrix. These catalyst properties contribute to the improved ORR kinetic current density and mass transport. By controlling synthesis chemistry, the correlation between structure and property is systematically investigated. The iron content is the most critical material property and can regulate site density and graphitic carbon structures in the catalyst, impacting catalytic activity and stability. The enhanced performance and durability were examined in both acidic aqueous electrolytes and membrane electrode assemblies.