| 研究実績の概要 |
Research objectives planned for this year included synthesis and characterization of nickel coordination polymers. Three coordination polymers (CPs), namely nickel dithiooxamide Ni(dto), iron-doped Fe-Ni(dto) and Ni2S were synthesized. High-pressure synthesis was used to prepare Ni2S. The complexes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating disk electrode (RDE) technique.
Electrochemical cycling of Ni(dto), dispersed in carbon matrix, in the potential range of 0.4 to 1.6 V vs. RHE, resulted in the formation of gamma-NiOOH which was found active towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline solutions. The nanocomposite showed an enhanced ORR activity with the onset potential of 0.81 V and the half-wave potential of 0.74 V vs. RHE in O2-saturated 1 M KOH solutions. The reduction of O2 on γ-NiOOH is found to proceed via 2e process.
The overpotential for OER on NiOOH/C was 390 mV at I =12 mA/cm2. At the same current density, the OER overpotential for Fe-doped NiOOH was 308 mV. Fe doping was found to improve OER kinetics. The OER overpotential of the catalyst is lower than of the benchmark IrO2/C electrode, with the same material loading. This study unfolds the potential of in situ electrochemical transformation of 3d transition metal 2D chelate polymers to fabricate active and stable electrocatalysts.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The project proceeds ahead of the schedule as many meetings could be held online. A research paper describing catalytic activity of copper dithiooxamide Cu(dto) in OER (Objective 4-2021) was published at the end of the 1st year of the grant term.
Synthesis of nickel coordination polymers (Ni(dto), Fe-Ni(dto), and NiS2) has been achieved and polymers were fully characterized for its activity towards OER in alkaline solutions. (Objective 5,6-2021).
A peer-reviewed paper was published as a part of Objective 7-2022. The results were presented at four international conferences (all held online due to Covid travel restrictions).
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| 今後の研究の推進方策 |
In accord with the originally proposed plan, in the third year of the project, work will focus on the characterization of Ni(dto)-derived electrocatalyst in the oxygen reduction reaction (ORR) in alkaline media. The results will be summarized into a research paper (Objective 7-2022). In addition, mono and dinuclear nickel coordination polymers (fluorinated and not) and Ni2S-HP will be characterized for its activity towards oxygen evolution reaction and oxygen reduction reaction in 1 M KOH using XRD, SEM-EDX, CV, LSV, RDE techniques.
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