| 研究実績の概要 |
We have succeeded in the preparation of three Fe nonporphyrin complexes with three different substituents (H, Cl, and F). The complexes were characterized with different spectroscopic techniques including 1H NMR, UV-vis, and mass spectroscopy. The complexes were investigated for the CO2 to CO conversion in nonaqueous DMF solutions . The complexes showed a CO2 reduction catalytic current with onset potentials shifted to more positive potentials on moving from the H to Cl to F substituents, achieving a relatively low overpotential of ~300 mV incase of the F substituents. The current density for the CO2
reduction reached a maximum of ~ 2 mA/cm2 at an overpotential of ~ 600 mV in the case of the Cl substituents. The F substituents showed a little lower current density of ~ 1.8 mA/cm2. These results are comparable with the most reported Fe porphyrin complexes, indicating our success in designing simply synthesised Fe nonporphyrin complexes. The selectivity of the Cl substituted complex for the CO2 to CO conversion was investigated using the gas chromatography, showing over 90% selectivity for the CO2 to CO formation which is also comparable with the Fe porphyrin complexes. The Cl complex was also grafited on the N-doped graphene through a covalent bonding to achieve efficient CO2 reduction in aqueous solutions. The Cl complex was also grafited on the carbon paper to achieve efficient CO2 reduction in aqueous solutions. Interestingly, the Cl complex showed activity for the water oxidation, indicating its bifunctionality for both CO2 reduction and water oxidation.
|
| 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
We designed these complexes mainly for the carbon dioxide to CO conversion using easily prepared Fe nonporphyrin complexes, and we plan to use them as cathode integrated with another water oxidation anode for complete carbon dioxide to CO conversion using the electrons and protons derived from the water oxidation. But, fortunately, we found that these complexes can serve as bifunctional catalysts for the two process. This will facilitate the design of a complete cell for the carbon dioxide to CO conversion in aqueous solutions using the same catalyst. Moreover, we succeeded in finding a way for grafting these complexes on several electrodes including the N-doped graphene and OH modified nickel foam to construct efficient cathode for carbon dioxide reduction and efficient anode for water oxidation in a complete aqueous medium.
|
| 今後の研究の推進方策 |
We will continue investigating the carbon dioxide to CO conversion selectivity of the Fe complex with the fluoro substituents in nonaqueous solution using gas chromatography. We will also graft this complex on carbon paper and N-doped graphene to construct an efficient cathode for carbon dioxide to CO conversion in aqueous solutions. Moreover we will modify the complex on the OH surface modified nickel foam for water oxidation. We will start the photoelectrochemical carbon dioxide to CO conversion with the three Fe complexes on nonaqueous solutions using ruthenium photosensitizer. We will modify these complexes on the surfaces of photocathodes such as CuO, CuBi2O4 and photonaodes such as BiVO4 and hematite for CO2 reduction and water oxidation, respectively. Finally electrolysis and photoelectrolysis cells will be constructed for the complete conversion.
|
