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submitted on 12.03.2020 and posted on 12.03.2020by Makoto Moriya, Ryo Takahama, Kazuki Kamoi, Junya Ohyama, Shin Kawashima, Ryoichi Kojima, Mariko Okada, Teruaki Hayakawa, Yuta Nabae
For the globalization of polymer
electrolyte fuel cells, the development of non-precious-metal (NPM) catalysts
for oxygen reduction is extremely important. To date, many NPM catalysts have
been synthesized by pyrolyzing Fe-, N-, and C-containing precursors, but they
suffer from the density and uncertain chemical structure of their active sites. This
study reports a 14-membered macrocyclic Fe complex, which was inspired by FeN4
centers in the pyrolyzed catalysts, whereas typical macrocyclic MN4
complexes have 16-membered rings. This 14-membered macrocycle has strong Fe-N
bonding with an average bond distance of 1.90 Å, which has been evidenced by
single-crystal X-ray diffraction, and is markedly shorter than that in
porphyrin, 2.0 Å. Promising electrocatalytic activities for oxygen reduction
have been demonstrated in both of acidic and basic media.