2022 Fiscal Year Annual Research Report
Pioneering 3d transition-metals coordination polymers as novel electrocatalysts for metal-air batteries.
| Project/Area Number |
20K05689
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| Research Institution | Shibaura Institute of Technology |
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Principal Investigator |
ジェズニチカ イザベラ 芝浦工業大学, 工学部, 教授 (40565769)
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| Co-Investigator(Kenkyū-buntansha) |
堀 顕子 芝浦工業大学, 工学部, 教授 (90433713)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | ORR / OER / electrocatalyst / chelate polymers / copper dithiooxamide / nickel dithiooxamide / bifunctional catalyst / metal-air batteries |
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| Outline of Annual Research Achievements |
In the field of metal-air batteries, a bifunctional electrocatalyst able to efficiently catalyze oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is highly desired to provide theoretically predicted high energy densities. To address this challenge we prepared copper and nickel coordination polymers with dithiooxamide (dto) and investigated their stability and electrocatalytic activity towards OER and ORR in alkaline solutions. Both Cu(dto) an Ni(dto) were obtained in high yields and their powders were used to formulate catalytic inks by mixing with carbon black and a binder. Cu(dto)-derived catalyst showed enhanced electrocatalytic activity for OER, with the overpotential of 280 mV (at 1mA/cm2) and a Tafel slope of 81 mV/dec in 1M KOH solutions. The catalyst was characterized by seven-fold higher current density per metal loading than commercially used IrO2/C catalyst. Cu(dto) showed however limited activity towards ORR. On the other hand, catalyst formulated with Ni(dto) showed bifunctional character. Particularly, it was found that γ-NiOOH, not β-NiOOH is active towards OER. The catalyst showed low overpotential not only for OER, but also for ORR in alkaline solutions. The onset potential for ORR was ~0.81 V vs. RHE, and the reaction was found to proceed via the 2e- transfer pathway. The high OER catalytic activity and relatively low ORR overpotential makes Ni(dto)-derived nanocomposite catalyst a good candidate for bifunctional OER/ORR catalyst which is stable in alkaline solutions.
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