Iron Phosphide Incorporated into Iron‐Treated Heteroatoms‐Doped Porous Bio‐Carbon as Efficient Electrocatalyst for the Oxygen Reduction Reaction

• Published in: ChemElectroChem Vol. 5; no. 14; pp. 1944 - 1953
• Main Authors: Tran, Thanh‐Nhan, Song, Min Young, Kang, Tong‐Hyun, Samdani, Jitendra, Park, Hyean‐Yeol, Kim, Hasuck, Jhung, Sung Hwa, Yu, Jong‐Sung
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 11.07.2018
• Subjects: Acid leaching; Ammonia pressure leaching; biomass; Carbon; Catalysis; Electrocatalysts; heteroatoms doping; Human wastes; Iron; iron phosphide; Leaching; oxygen reduction reaction; Oxygen reduction reactions; Phosphides; Porosity; porous carbon; Precursors; Pyrolysis; Structural hierarchy; Synergistic effect; Urine
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201800091

The development of electrocatalysts from inexpensive, natural sources has been an attractive subject owing to economic, environmental, sustainable, and social merits. Herein, Fe‐treated heteroatoms (N, P, and S)‐doped porous carbons are synthesized for the first time by pyrolysis of bio‐char derived from abundant human urine waste as a single precursor for carbon and heteroatoms, using iron(III) acetylacetonate as an external Fe precursor, followed by acid leaching and activation with a second pyrolysis step in NH3. In particular, the sample prepared at a pyrolysis temperature of 800 °C (FeP‐NSC‐800) contains iron phosphide (FeP, Fe2P) in the high‐porosity heteroatoms‐doped carbon framework along with Fe traces, and exhibits excellent oxygen reduction reaction (ORR) activity and stability in both alkaline and acidic electrolytes as demonstrated in half‐ and single‐cell tests. Such excellent ORR catalytic performance is ascribed to a synergistic effect of not only multiple active Fe−P, Fe−N, and pyridinic and graphitic N species in the electrocatalyst but also facile transport channels provided by its hierarchical porous structure with micro‐/mesopores. In addition, the sample exhibits high long‐term durability and methanol crossover resistance. Nothing goes to waste: Template‐free synthesis of new active Fe‐treated heteroatoms (N, P, and S)‐doped bio‐carbon electrocatalysts is reported for the first time by simple pyrolysis of bio‐char derived from human urine and Fe (III) precursor. The optimized sample contains iron phosphide (FeP and Fe2P) incorporated in carbon framework, and exhibits remarkable ORR catalytic activity and stability in both alkaline and acidic media.