Structure of Active Sites of Fe-N-C Nano-Catalysts for Alkaline Exchange Membrane Fuel Cells
Hirofumi Kishi,
Tomokazu Sakamoto,
Koichiro Asazawa,
Susumu Yamaguchi,
Takeshi Kato,
Barr Zulevi,
Alexey Serov,
Kateryna Artyushkova,
Plamen Atanassov,
Daiju Matsumura,
Kazuhisa Tamura,
Yasuo Nishihata,
Hirohisa Tanaka
Affiliations
Hirofumi Kishi
Advanced R&D Department, Daihatsu Motor Co. Ltd., 3000 Yamanoue, Ryuo, Gamo, Shiga 520-2593, Japan
Tomokazu Sakamoto
Advanced R&D Department, Daihatsu Motor Co. Ltd., 3000 Yamanoue, Ryuo, Gamo, Shiga 520-2593, Japan
Koichiro Asazawa
Advanced R&D Department, Daihatsu Motor Co. Ltd., 3000 Yamanoue, Ryuo, Gamo, Shiga 520-2593, Japan
Susumu Yamaguchi
Advanced R&D Department, Daihatsu Motor Co. Ltd., 3000 Yamanoue, Ryuo, Gamo, Shiga 520-2593, Japan
Takeshi Kato
Advanced R&D Department, Daihatsu Motor Co. Ltd., 3000 Yamanoue, Ryuo, Gamo, Shiga 520-2593, Japan
Barr Zulevi
Pajarito Powder Limited Liability Company (LLC), 3600 Osuna Rd NE, Suite 309, Albuquerque, NM 87102, USA
Alexey Serov
Pajarito Powder Limited Liability Company (LLC), 3600 Osuna Rd NE, Suite 309, Albuquerque, NM 87102, USA
Kateryna Artyushkova
Department of Chemical & Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA
Plamen Atanassov
Department of Chemical & Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA
Daiju Matsumura
Quantum Beam Science Center, Japan Atomic Energy Agency, 1-1-1, Koto, Sayo, Hyogo 679-5148, Japan
Kazuhisa Tamura
Quantum Beam Science Center, Japan Atomic Energy Agency, 1-1-1, Koto, Sayo, Hyogo 679-5148, Japan
Yasuo Nishihata
Quantum Beam Science Center, Japan Atomic Energy Agency, 1-1-1, Koto, Sayo, Hyogo 679-5148, Japan
Hirohisa Tanaka
Department of Nanotechnology for Sustainable Energy, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
Platinum group metal-free (PGM-free) catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of ex situ and in situ synchrotron X-ray spectroscopy techniques; high-resolution Transmission Electron Microscope (TEM); Mößbauer spectroscopy combined with electrochemical methods and Density Functional Theory (DFT) modeling/theoretical approaches. The main objective of this study was to correlate the HO2− generation with the chemical nature and surface availability of active sites in iron-nitrogen-carbon (Fe-N-C) catalysts derived by sacrificial support method (SSM). These nanomaterials present a carbonaceous matrix with nitrogen-doped sites and atomically dispersed and; in some cases; iron and nanoparticles embedded in the carbonaceous matrix. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Combining spectroscopy, microscopy and electrochemical reactivity allowed the building of structure-to-properties correlations which demonstrate the contributions of these moieties to the catalyst activity, and mechanistically assign the active sites to individual reaction steps. Associated with Fe-Nx motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition; processing and treatment conditions of SSM. From the results of material characterization; catalytic activity and theoretical studies; Fe metallic particles (coated with carbon) are main contributors into the HO2− generation.
