Iron Phosphide Incorporated in Iron-Treated Porous Bio-Carbon as Efficient Electrocatalysts for Oxygen Reduction Reaction

T-N. Tran, I-S. So, J-S. Yu
Daegu Gyeongbuk Institute of Science and Technology (DGIST),
Korea

Keywords: iron phosphide, porous carbon, electrocatalyst, oxygen reduction reaction, bio-carbon

Summary:

Development of electrocatalysts from cheap natural sources has been an attractive subject owing to the economic, environmental, sustainable, and social merits [1,2]. 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 precuror for carbon and heteroatoms, using iron (III) acetylacetonate as an external Fe precursor, followed by acid leaching and activation with second pyrolysis in NH3 [3]. In particular, the sample prepared at pyrolysis temperature of 800 oC (FeP-NSC-800) contains iron phosphide (FeP, Fe2P) in high porosity heteroatoms-doped carbon framework along with Fe traces, and exhibits excellent 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 synergistic effect of not only multiple active Fe-P, Fe-N and pyridinic and graphitic N species in Fe-treated heteroatoms-doped carbon 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.