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Active Motif Change of Ni-Fe Spinel Oxide by Ir Doping for Highly Durable and Facile Oxygen Evolution Reaction |
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| Authors: | Sukhwa Hong Kahyun Ham Jeemin Hwang Sinwoo Kang Min Ho Seo Young-Woo Choi Byungchan Han Jaeyoung Lee Kangwoo Cho |
| Affiliation: | 1. Division of Environmental Science & Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang, 37673 Republic of Korea;2. School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea
International Future Research Center of Chemical Energy Storage and Conversion Processes, GIST, 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea Ertl Center for Electrochemistry and Catalysis, GIST, 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea;3. Fuel Cell Research & Demonstration Center, Hydrogen Energy Research Division, Korea Institute of Energy Research (KIER), 20–41 Sinjaesaengeneogi-ro, Haseo-myeon, Buan-gun, Jeollabuk-do, 56332 Republic of Korea;4. School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea International Future Research Center of Chemical Energy Storage and Conversion Processes, GIST, 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea;5. Department of Nanotechnology Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan, 48547 Republic of Korea;6. Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul, 03722 Republic of Korea;7. School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Gwangju, 61005 Republic of Korea |
| Abstract: | The oxygen evolution reaction (OER) is crucial for producing sustainable energy carriers. Herein, Ir (5 mol.%) doped inverse-spinel NiFe2O4 (Ir-NFO) nanoparticles deposited on Ni foam (NF) by scalable solution casting are considered a promising OER electrocatalyst for industrial deployments. The Ir-NFO/NF (with minimal lattice distortion by uniform Ir doping) provides an OER overpotential of 251 mV (intrinsically outperforming NFO/NF and benchmarking IrO2/NF) and extraordinary robustness over 130 days at 100 mA cm?2. In situ X-ray absorption spectroscopy reveals oxidation only for Fe on NFO, whereas concurrent generation of higher-valent Ni and Fe occurs on Ir-NFO during OER. Density functional theory calculations further demonstrate that Ir substitutes the sublayer Ni octahedral site and switches the main active reaction center from FeOh? FeTd bridge site (Fe? O? Fe) on NFO to NiOh–FeTd bridge site (Ni? O? Fe active motif) on Ir-NFO for a co-catalytic OER. This study sheds new light on precious-metal doped Ni-Fe oxides, which may be applicable to other binary/ternary oxide electrocatalysts. |
| Keywords: | density functional theory calculation doping effect in situ X-ray absorption spectroscopy oxygen evolution reaction spinel oxide |