title: Phenylenediamine-based FeN(x)/C catalyst with high activity for oxygen reduction in acid medium and its active-site probing.
abstract: High-temperature pyrolyzed FeN(x)/C catalyst is one of the most promising nonprecious metal electrocatalysts for oxygen reduction reaction (ORR). However, it suffers from two challenging problems: insufficient ORR activity and unclear active site structure. Herein, we report a FeN(x)/C catalyst derived from poly-m-phenylenediamine (PmPDA-FeN(x)/C) that possesses high ORR activity (11.5 A g(-1) at 0.80 V vs RHE) and low H2O2 yield (<1%) in acid medium. The PmPDA-FeN(x)/C also exhibits high catalytic activity for both reduction and oxidation of H2O2. We further find that the ORR activity of PmPDA-FeN(x)/C is not sensitive to CO and NO(x) but can be suppressed significantly by halide ions (e.g., Cl(-), F(-), and Br(-)) and low valence state sulfur-containing species (e.g., SCN(-), SO2, and H2S). This result reveals that the active sites of the FeN(x)/C catalyst contains Fe element (mainly as Fe(III) at high potentials) in acid medium.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Zhi-You
authors.initials: ZY
authors.lastname: Zhou
authors.forename: Yu-Jiao
authors.initials: YJ
authors.lastname: Lai
authors.forename: Yong
authors.initials: Y
authors.lastname: You
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Liu
authors.forename: Xia-Ling
authors.initials: XL
authors.lastname: Wu
authors.forename: Ephrem
authors.initials: E
authors.lastname: Terefe
authors.forename: Chi
authors.initials: C
authors.lastname: Chen
authors.forename: Lin
authors.initials: L
authors.lastname: Song
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rauf
authors.forename: Na
authors.initials: N
authors.lastname: Tian
authors.forename: Shi-Gang
authors.initials: SG
authors.lastname: Sun