Quaternary FeCoNiMn-Based Nanocarbon Electrocatalysts for Bifunctional Oxygen Reduction and Evolution: Promotional Role of Mn Doping in Stabilizing Carbon
- Univ. at Buffalo, NY (United States). Dept. of Chemical and Biological Engineering
- Giner Inc., Newton, MA (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
- Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering
The intrinsic instability of carbon largely limits its use for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a bifunctional catalyst in reversible fuel cells or water electrolyzers. In this paper, we discovered that Mn doping has a promotional role in stabilizing nanocarbon catalysts for the ORR/OER in alkaline media. Stable nanocarbon composites are derived from an inexpensive carbon/nitrogen precursor (i.e., dicyandiamide) and quaternary FeCoNiMn alloy via a template-free carbonization process. In addition to FeCoNiMn metal alloys/oxides, the carbon composites comprise substantial carbon tube forests growing on a thick and dense graphitic substrate. The dense carbon substrate with high degree of graphitization results from Mn doping, while active nitrogen-doped carbon tubes stem from FeCoNi. Catalyst structures and performance are greatly dependent on the doping content of Mn. Various accelerated stress tests (AST) and life tests verify the encouraging ORR/OER stability of the nanocarbon composite catalyst with optimal Mn doping. Extensive characterization before and after ASTs elucidates the mechanism of stability enhancement resulting from Mn doping, which is attributed to (i) hybrid carbon nanostructures with enhanced resistance to oxidation and (ii) the in situ formation of the β-MnO2 and FeCoNi-based oxides capable of preventing carbon corrosion and promoting activity. Note that the improvement in stability due to Mn doping is accompanied by a slight activity loss due to a decrease in surface area. Finally, this work provides a strategy to stabilize carbon catalysts by appropriately integrating transition metals and engineering carbon structures.
- Research Organization:
- Giner Inc., Newton, MA (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Univ. at Buffalo, NY (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Hydrogen Fuel Cell Technologies Office; USDOE Office of Science (SC); National Science Foundation (NSF)
- Grant/Contract Number:
- SC0012704; EE0006960; CBET-1604392
- OSTI ID:
- 1425082
- Report Number(s):
- BNL-203254-2018-JAAM
- Journal Information:
- ACS Catalysis, Vol. 7, Issue 12; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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