Effect of Iron Precursors on the Structure and Oxygen Reduction Activity of Iron–Nitrogen–Carbon Catalysts. (1st September 2016)

• Record Type: Journal Article
• Authors: Setyowati, Vuri Ayu; Huang, Hsin-Chih; Liu, Chia-Chi; Wang, Chen-Hao
• Is Part Of: Electrochimica acta. Volume 211(2016)
• Page Start: 933
• Page End: 940
• Publication Date: 2016-09-01
• Subjects: non-precious metal catalyst -- oxygen reduction reaction -- Fe-N-C catalyst -- precursor effect; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2016.06.112
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: To understand the effect of an iron precursor on the structure and oxygen reduction activity of an Iron–Nitrogen–Carbon (Fe–N–C) catalyst, several iron precursors, FeCl3, FeCl2, Fe(C2 H3 O2 )2, and FeSO4, were mixed with polyaniline (PANI) and carbon black and then pyrolyzed at 700 °C under a nitrogen atmosphere; the obtained nonprecious metal catalysts were denoted as FeCl3 –PANI/C, FeCl2 –PANI/C, Fe(C2 H3 O2 )2 –PANI/C, and Fe2 SO4 –PANI/C, which were compared for the activity of oxygen reduction reaction (ORR) in acidic media and characterized through X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption near-edge spectroscopy, and extended X-ray absorption fine structure. The ORR activity of the catalysts was ranked in the following order: FeCl3 –PANI/C, FeCl2 –PANI/C, Fe(C2 H3 O2 )2 –PANI/C, and Fe2 SO4 –PANI/C, where the electron-transfer numbers were 3.99, 3.98, 3.94, and 3.83, respectively. FeCl3 –PANI/C and FeCl2 –PANI/C exhibited Fe–N4 structures and Fe 3+ chelates, in which a large amount of quaternary-type nitrogen and pyrrolic-type nitrogen but a small amount of cyanide were formed in the catalysts. Fe(C2 H3 O2 )2 –PANI/C showed that Fe–N4 structures and Fe 2+ chelates were formed mostly in the catalyst, but showed the lowest nitrogen content among all catalysts. Fe2 SO4 –PANI/C was composed of FeS and Fe2 O3 compounds. These results indicated that iron precursors affected the carbon–nitrogen composition, iron oxidation state of iron chelate, and chelate structure of Fe–N–C catalysts, resulting in the change of the ORR activity.