Oxygen vacancy-originated highly active electrocatalysts for the oxygen evolution reaction

Shigeto Hirai, Kazuki Morita, Kenji Yasuoka, Taizo Shibuya, Yujiro Tojo, Yoichi Kamihara, Akira Miura, Hisao Suzuki, Tomoya Ohno, Takeshi Matsuda, Shunsuke Yagi

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The oxygen evolution reaction (OER) is an important reaction in the field of renewable energy and is utilized in electrochemical water splitting for hydrogen fuel production and rechargeable metal-air batteries. Herein, we report a new oxygen evolution reaction mechanism originating from oxygen vacancies, which remarkably enhances the OER activity of oxygen deficient electrocatalysts. The OER activity of Sr2VFeAsO3-δ is drastically enhanced above the lattice oxygen vacancy of δ = 0.5, exhibiting ∼300 mV lower overpotential and 80 times higher specific activity at 1.7 V vs. RHE. Surprisingly, the initially low OER activity of Sr2VFeAsO3-δ (δ < 0.5) is enhanced to the level of state-of-the-art OER catalysts simply by introducing higher concentrations of oxygen vacancies. Density functional theory (DFT) calculations clarify that the oxygen vacancies are initially dominated by one of the crystallographic sites, while two types of crystallographic sites become fully accessible for δ > 0.5. As a result, the distance between OH- coupled oxygen-vacant sites becomes sufficiently short to enable direct O-O bond formation as in photosystem II. Thus, we found that the OER activity of oxygen deficient electrocatalysts is controllable by the variety of lattice oxygen vacancies, which suggests that oxygen deficient layered superconductors are promising OER catalysts for energy conversion technologies.

Original languageEnglish
Pages (from-to)15102-15109
Number of pages8
JournalJournal of Materials Chemistry A
Volume6
Issue number31
DOIs
Publication statusPublished - 2018 Jan 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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