Abstract
Nitrogen-doped porous carbons containing atomically dispersed iron are prime candidates for substituting platinum-based catalysts for oxygen reduction reaction (ORR) in fuel cells. These carbon catalysts are classically synthesized via complicated routes involving multiple heat-treatment steps to form the desired Fe-Nx sites. We herein developed a highly active Fe–N–C catalyst comprising of exclusive Fe-Nx sites by a simplified solid-state synthesis protocol involving only a single heat-treatment. Imidazole is pyrolyzed in the presence of an inorganic salt-melt resulting in highly porous carbon sheets decorated with abundant Fe-Nx centers, which yielded a high density of electrochemically accessible active sites (1.36 × 1019 sites g−1) as determined by the in situ nitrite stripping technique. The optimized catalyst delivered a remarkable ORR activity with a half-wave potential (E1/2) of 0.905 VRHE in alkaline electrolyte surpassing the benchmark Pt catalyst by 55 mV. In acidic electrolyte, an E1/2 of 0.760 VRHE is achieved at a low loading level (0.29 mg cm−2). In PEMFC tests, a current density of 2.3 mA cm−2 is achieved at 0.90 ViR-free under H2–O2 conditions, reflecting high kinetic activity of the optimized catalyst.
Original language | English |
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Pages (from-to) | 148-157 |
Number of pages | 10 |
Journal | Journal of Colloid and Interface Science |
Volume | 596 |
DOIs | |
State | Published - 15 Aug 2021 |
Keywords
- Fe–N–C
- Fuel cells
- Non-precious metal catalysts
- Oxygen reduction reaction
- Site density