Cu, Fe, N-doped Carbon Nanotubes Prepared through Silica Coating for Selective Oxygen Reduction to Water in Acidic Media

Masaru Kato, Daiki Abe, Siqi Xie, Shun Sato, Natsuki Fujibayashi, Koki Matsumoto, Akira Onoda, Takashi Hayashi, Takaya Mitsui, Kosuke Fujiwara, Takashi Yamamoto, Yasuaki Einaga, Colin A. Tadgell, Yuta Kato, Kiyotaka Asakura, Ichizo Yagi

Research output: Contribution to journalArticlepeer-review

Abstract

We report Cu, Fe, N-doped carbon nanotubes, (Cu,Fe)−N−CNT, as electrocatalysts for the oxygen reduction reaction (ORR) in acidic media. (Cu,Fe)−N−CNT was prepared using a silica coating method in pyrolysis to minimize the formation of carbon-coated metal oxide or carbide nanoparticles, which are known to be inactive for the H2O2 reduction. (Cu,Fe)−N−CNT shows a turnover frequency of 0.66 e site−1 s−1 at +0.8 V vs. RHE and H2O2 yields of <1 % for the ORR with a utilization factor of active sites of 82 %. Kinetic analysis reveals that 4e transfer rates for (Cu,Fe)−N−CNT are higher than those of a monometallic counterpart of Fe−N−CNT. In situ X-ray absorption spectroscopy enables us to determine redox potentials: E°’(FeIII/FeII)=0.65 V vs. RHE and E°’(CuII/CuI)=0.45 V for (Cu,Fe)−N−CNT, and E°’(FeIII/FeII)=0.65 V for Fe−N−CNT. These results indicate that bimetallic doping into carbon nanotubes gives the effect on kinetic parameters but not on thermodynamic ones. In other words, there is no direct electronic interactions between the Cu and Fe active sites for (Cu,Fe)-N-CNT because such interactions should modulate their redox potentials.

Original languageEnglish
JournalChemCatChem
DOIs
Publication statusAccepted/In press - 2024

Keywords

  • bio-inspired electrocatalysts
  • dual atom catalysts
  • heterometallic cooperativity
  • kinetic analysis
  • oxygen reduction reaction

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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