研究実績の概要 |
Hydrogen peroxide is an important green oxidant widely used in a variety of industries and a promising clean fuel for jet car and rockets. However, the apparent quantum yield for non-sacrificial hydrogen peroxide production is still out of satisfaction. Firstly, we engineered the band structure and improved charge separation properties, and this improved hydrogen peroxide production. Then, we seek the other appropriate ORR sites with a novel guideline. Furthermore, we prepared antimony single-atom catalyst. A record-high apparent quantum yield together with a solar-to-chemical conversion efficiency for hydrogen peroxide synthesis was achieved.
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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 researcher studied polymeric carbon nitride (PCN)-based photocatalysts for non-sacrificial H2O2 production using O2, water and visible light. The representative work of his PhD study is the synthesis of Sb-based single-atom photocatalyst (SAPC) by isolating Sb3+ sites in the matrix of PCN via a solid-state reaction (SSR). The solar-to-chemical conversion efficiency reaches 0.61%, along with a high external quantum efficiency (EQE) of 17% at 420 nm, in non-sacrificial H2O2 production. This work was accepted for publication in Nature Catalysis. In this work and another related work published in Appl. Catal. B-Environ., the applicant proposed a theoretical guideline for predicting the charge separation, charge transfer and reaction sites of SAPCs for H2O2 production based on the density functional theory (DFT), time-dependent DFT (TDDFT) and population analysis of wave functions. The applicant compared the density of states, charge separation properties and delocalization properties of the electrons and holes at the ground state and the excited states. The reliability of this guideline was further confirmed from experimentally observed catalytic performance, action spectra, transition absorption spectroscopy and quasi in-situ Raman spectra. Because the theoretical guideline developed by the applicant was general and effective, it was used to predict/explain the charge separation properties and reaction sites for not only photocatalytic H2O2 production but selective oxidation of methene to methanal in follow-up studies involving international collaborative groups.
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今後の研究の推進方策 |
Inorganic semiconductors usually have large permittivity, leading to a small exciton binding energy and thus more efficient charge transfer. In this case, there is an urgent need for the applicant to expand the research field from current organic semiconductors to inorganic ones. The a guideline for predicting the charge separation, charge transfer and surface properties could not be restricted in the field of organic semiconductors but expanded to inorganic ones (For instance, GaN:ZnO, BaTaON and Ta3N5 in Domen's Lab). A general methodology for predicting the relations between the structure, property and performance of a certain photocatalyst could be established after he accomplished this fellowship in future.
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