Single-Iron Site Catalysts with Self-Assembled Dual-size Architecture and Hierarchical Porosity for Proton-Exchange Membrane Fuel Cells
Single-Iron Site Catalysts with Self-Assembled Dual-size Architecture and Hierarchical Porosity for Proton-Exchange Membrane Fuel Cells
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DOI：
10.1016/j.apcatb.2020.119400
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发表时间：
2020-12
影响因子：
22.1
通讯作者：
Xiaolin Zhao;Xiaoxuan Yang;Maoyu Wang;Sooyeon Hwang;S. Karakalos;Mengjie Chen;Zhi Qiao;Lei Wang-Lei-Wa
中科院分区：
文献类型：
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作者：
Xiaolin Zhao;Xiaoxuan Yang;Maoyu Wang;Sooyeon Hwang;S. Karakalos;Mengjie Chen;Zhi Qiao;Lei Wang-Lei-Wa
原子分散和氮配位的单个铁位点（即，Fe-N-C催化剂是质子交换膜燃料电池（PEMFC）中最有前途的无铂族金属（PGM）的氧还原反应（ORR）阴极。然而，目前的Fe-N-C催化剂受到活性FeN 4位点暴露不足的限制，这是由于颗粒在阴极中不可避免的团聚。在此，我们报告了一种自组装策略，通过使用大颗粒来支撑小颗粒，合成具有来自双尺寸Fe掺杂的ZIF-8晶体前体的分级多孔基质的原子分散的FeN 4位催化剂。定制的结构在减轻颗粒迁移、团聚和空间重叠方面是有效的，从而暴露增加的可接近的活性位点并促进质量传输。由30 nm“卫星”组装的100 nm“成核种子”组成的性能最好的催化剂在酸性电解质和膜电极组件中表现出优异的ORR活性。本工作为设计具有单金属原子分散的分级多孔催化剂提供了新的概念，通过自组装具有可调粒径和纳米结构的ZIF-8晶体前体。
Atomically dispersed and nitrogen coordinated single iron site (i.e., FeN4) catalysts (Fe-N-C) are the most promising platinum group metal (PGM)-free cathode for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs). However, current Fe-N-C catalysts are limited by the inferior exposure of active FeN4sites due to the inevitable agglomeration of particles in cathodes. Herein, we report a self-assembled strategy to synthesize the atomically dispersed FeN4site catalysts with a hierarchically porous matrix derived from dual-size Fe-doped ZIF-8 crystal precursors by using large particles to support small particles. The tailored structure is effective in mitigating the particle migration, agglomeration, and spatial overlap, thereby exposing increased accessible active sites and facilitating mass transport. The best performing catalyst composed of 100 nm “nucleated seed” assembled by 30 nm “satellite” demonstrates exceptional ORR activity in acidic electrolyte and membrane electrode assembly. This work provides new concepts for designing hierarchically porous catalysts with single metal atom dispersionviaself-assembly of ZIF-8 crystal precursors with tunable particle sizes and nanostructures.