Abstract
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 FeN4 sites due to the inevitable agglomeration of particles in cathodes. Herein, we report a self-assembled strategy to synthesize the atomically dispersed FeN4 site 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 dispersion via self-assembly of ZIF-8 crystal precursors with tunable particle sizes and nanostructures.
Original language | English |
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Article number | 119400 |
Journal | Applied Catalysis B: Environmental |
Volume | 279 |
DOIs | |
State | Published - Dec 15 2020 |
Funding
This work is financially supported by the University at Buffalo , SUNY , National Science Foundation (NSF) (CBET-1604392, 1804326 ), and U.S. DOE-EERE Fuel Cell Technologies Office ( DE-EE0008076 ). Electron microscopy research was conducted at the Center for Functional Nano-materials at Brookhaven National Laboratory and Oak Ridge National Laboratory. X-ray absorption spectroscopy research used resources of the beamline 5-BM, DND-CAT at the Advanced Photon Source (APS) that is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. DND-CAT is supported through E. I. duPont de Nemours & Co., Northwestern University, and The Dow Chemical Company. This work is financially supported by the University at Buffalo, SUNY, National Science Foundation (NSF) (CBET-1604392, 1804326), and U.S. DOE-EERE Fuel Cell Technologies O?ce (DE-EE0008076). Electron microscopy research was conducted at the Center for Functional Nano-materials at Brookhaven National Laboratory and Oak Ridge National Laboratory. X-ray absorption spectroscopy research used resources of the beamline 5-BM, DND-CAT at the Advanced Photon Source (APS) that is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. DND-CAT is supported through E. I. duPont de Nemours & Co. Northwestern University, and The Dow Chemical Company.
Keywords
- Single metal sites
- electrocatalysis
- fuel cells
- oxygen reduction
- self-assembly architecture