期刊
ACS CATALYSIS
卷 4, 期 9, 页码 3193-3200出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs500807v
关键词
oxygen reduction; nonprecious metal catalysis; phosphate tolerance; Pt poisoning; phosphoric acid fuel cells
资金
- DOE-EERE Fuel Cell Technologies Office
- ORNL's Center for Nanophase Materials Sciences (CNMS)
- Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. DOE
Increased oxygen reduction reaction (ORR) kinetics, improved CO tolerance, and more efficient water and heat management represent significant advantages that high-temperature polymer electrolyte fuel cells (HT-PEFCs) operating with a phosphoric acid-doped polybenzimidazole (PBI) membrane offer over traditional Nafion-based, low-temperature PEFCs. However, before such HT-PEFCs become viable, the detrimental effect of phosphate chemisorption on the performance of state-of-the-art wt-based cathode catalysts needs to be addressed. In this study, we propose a solution to the severe poisoning of Pt-based PEFC cathode catalysts with phosphates (H2PO4 and HPO42-) by replacing standard Pt/C catalysts with phosphate-tolerant, nonprecious metal catalyst (NPMC) formulations. Catalysts with a very high surface area (845 m(2) g (-1)) were synthesized in this work from polyaniline (PANI), iron, and carbon using a high-temperature approach. The effects of metal precursors and metal loading on the morphology, structure, and ORR activity of the NPMCs were systematically studied. Electrochemical measurements indicated that as-prepared Fe-based catalysts (PANI-Fe-C) can tolerate phosphate ions at high concentrations and deliver ORR performance in 5.0 M H3PO4 that is superior to that of Pt/C catalysts. A 30 wt 96 Fe-derived catalyst was found to have the most porous morphology and the highest surface area among studied Fe-based catalysts, which correlates with the highest ORR activity of that catalyst. These cost-effective and well-performing ORR catalysts can potentially replace Pt/C catalysts in phosphoric acid-based HT-PEFCs.
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