記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

As one of the most promising molecular catalyst sensitized systems (MCSS) for an artificial photosynthesis, photochemical two-electron water oxidation into hydrogen peroxide catalyzed by tetra-pyridylporphyrinatetinIV (SnTPyP) adsorbed on SnO2 nanoparticles fabricated as a photoanode upon one-photon visible-light excitation was examined. Unimolecular SnTPyPaxial/SnO2 covalently bound through an axial ligand O atom (1), cationic unimolecular (SnTPyP(PrBr)4)axial/SnO2 covalently bound through an axial ligand O atom (2), cationic unimolecular (SnTPyP(PrBr)4)ionic/SnO2 bound through ionic interaction (3), cationic oligomer ((SnTPyP(PrBr)4)ionic)4/SnTPyPaxial/SnO2 with only the central SnTPyP covalently bound through axial coordination (4), cationic oligomer ((SnTPyP(PrBr)4)axial)4/SnTPyPaxial/SnO2 with all five SnTPyPs covalently bound through axial coordination (5), cationic oligomer ((SnTPyP(PrBr)4)ionic)3/SnTPyPsilyl/SnO2 covalently bound through silylation of the SnO2 surface (6), and unimolecular SnTPyPsilyl/SnO2 covalently bound through silylation of the SnO2 surface (7) were fabricated as the photoanodes, and their photoelectrochemical behavior was examined to characterize five factors: the absorbed photon to current efficiency (APCE), light harvesting efficiency (LHE), durability as the time period for 90% decay from the initial photocurrent (T90%), amount of H2O2 accumulation, and Faradaic yield of H2O2 formation. The unimolecular silylated SnTPyPsilyl/SnO2 (7) exhibited the highest APCE (45%), which could be caused by a swing motion of propylsilyloxyl bridging moieties to make one-electron oxidized SnTPyP away from the SnO2 surface just after an electron injection from the excited SnTPyP into the conduction band of SnO2 and to facilitate the charge separation by retarding the charge recombination process. On the other hand, the unimolecular SnTPyP covalently bound through coordination of an axial ligand atom (1) exhibited a modest APCE (11%), which faces rather intimately with the SnO2 surface to undergo substantial charge recombination. The modest reactivity was similarly observed for oligomeric SnTPyPs (5: APCE 12%) with all five porphyrins being covalently bound to the SnO2 surface suffering enhanced charge recombination. Other oligomeric SnTPyPs, 4 (APCE 22%) and 6 (APCE 29%), showed moderate reactivity owing to a presumed hole hopping among SnTPyPs within oligomers enabling the better charge separation. All the oligomers (4, 5, and 6) with strongly light absorptive SnTPyPs exhibited better LHE than unimolecular systems and better durability (T90%) by hanging over the SnO2 surface to protect from an attack of hydronium ion (H3O+) leading to a substantial desorption of SnTPyPs under the acidified conditions caused by a microscopic pH jumping effect in the narrow gap space between SnO2 nanoparticles, emphasizing the privileged situation for the oligomeric systems.

DOI： 10.1021/acs.jpcc.4c05813

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Sustainable Chemistry and Engineering  

[FeFe]-hydrogenase (HydA) is an active biocatalytic enzyme for solar-to-hydrogen (H2) conversion. However, stability is a main challenge that limits practical applications. This work aims to encourage the efficiency of HydA by encapsulating it in the zeolitic imidazolate framework-8 (ZIF-8) as a synthetic protective shield. The construction of HydA@ZIF-8 nanoparticles, with an average diameter of 700-1000 nm, at ambient conditions can preserve HydA activity within a spatially confined microenvironment, as characterized by scanning electron microscopy and X-ray diffraction analysis. Based on MV•+-dependent H2 production activity and kinetic analysis, both the stability and efficiency of HydA@ZIF-8 surpass those of free HydA and whole-cell biocatalysts over a wider range of pH and temperature. The achievement of robust HydA@ZIF-8 construction represents a significant step forward in the development of biocatalysts for various future applications.

DOI： 10.1021/acssuschemeng.3c08560

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Catalysis B: Environmental  

NH3 is an important chemical fertilizer and expecting as H2 carrier. Several methods have been investigated for eco-friendly NH3 production under mild conditions instead of Haber-Bosch process using 400 °C, 20 MPa. Here, cyanobacterial Anabaena variabilis was utilized as a nitrogenase-producing biocatalyst that converts N2/H2O to NH3 under ambient conditions. Biocatalytic reactions revealed that MV•+ can penetrate cell membrane and transfer electrons generated in inorganic photocatalyst. We first reported photobiocatalytic NH3 production of cyanobacteria and TiO2. Comparing with natural system, NH3 formation rate of the hybrid system increased 81.3 times with an initial rate of 2031.7 nmol·h−1 and turnover number of 216.8.

DOI： 10.1016/j.apcatb.2023.123431

Web of Science

Scopus

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

開催年月日： 2024年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Emmy-Noether-Saal, Conference and Event House Alte Mensa, Göttingen, Germany   国名：ドイツ連邦共和国  

担当区分：責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）